Pub Date : 2022-10-27DOI: 10.1080/03091929.2023.2220877
A. Sukhanovskii, E. Popova, A. Vasiliev
A new shallow layer laboratory model of global atmospheric circulation is realised and studied by experiments and numerical simulations. A shallow rotating cylindrical fluid layer of 30 mm thickness and 690 mm diameter, with a localised heater at the bottom periphery and localised cooler in the central part of the upper boundary is considered. The rim heater imitates the equator heating and disc cooler – the North pole cooling. The flow transforms from the Hadley-like regime to the baroclinic wave regime through transitional states. The decrease in the thermal Rossby number for the fixed value of Taylor number results in the regularisation of the baroclinic waves. All wave regimes, even with regular wave structures, are characterised by strong non-periodic fluctuations. The observed baroclinic wave structures are a combination of temporarily evolving different baroclinic modes. The important outcome of the shallow layer model is a realisation of the Earth-like meridional three-cell structure. It is shown that the three-cell structure with analogs of polar, Ferrel and Hadley cells exist only in a limited range of parameters. A comparison of the results for the water and silicon oil demonstrated that the physical properties of the fluid can have a strong impact on the baroclinic wave structure.
{"title":"A shallow layer laboratory model of large-scale atmospheric circulation","authors":"A. Sukhanovskii, E. Popova, A. Vasiliev","doi":"10.1080/03091929.2023.2220877","DOIUrl":"https://doi.org/10.1080/03091929.2023.2220877","url":null,"abstract":"A new shallow layer laboratory model of global atmospheric circulation is realised and studied by experiments and numerical simulations. A shallow rotating cylindrical fluid layer of 30 mm thickness and 690 mm diameter, with a localised heater at the bottom periphery and localised cooler in the central part of the upper boundary is considered. The rim heater imitates the equator heating and disc cooler – the North pole cooling. The flow transforms from the Hadley-like regime to the baroclinic wave regime through transitional states. The decrease in the thermal Rossby number for the fixed value of Taylor number results in the regularisation of the baroclinic waves. All wave regimes, even with regular wave structures, are characterised by strong non-periodic fluctuations. The observed baroclinic wave structures are a combination of temporarily evolving different baroclinic modes. The important outcome of the shallow layer model is a realisation of the Earth-like meridional three-cell structure. It is shown that the three-cell structure with analogs of polar, Ferrel and Hadley cells exist only in a limited range of parameters. A comparison of the results for the water and silicon oil demonstrated that the physical properties of the fluid can have a strong impact on the baroclinic wave structure.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"41 1","pages":"155 - 176"},"PeriodicalIF":1.3,"publicationDate":"2022-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76365234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-12DOI: 10.1080/03091929.2022.2107202
Stephen J. Mason, C. Guervilly, G. Sarson
ABSTRACT We report simulations of thermal convection and magnetic-field generation in a rapidly-rotating spherical shell, in the presence of a uniform axial magnetic field of variable strength. We consider the effect of the imposed field on the critical parameters (Rayleigh number, azimuthal wavenumber and propagation frequency) for the onset of convection, and on the relative importance of Coriolis, buoyancy and Lorentz forces in the resulting solutions. The imposed field strength must be of order one (corresponding to an Elsasser number of unity) to observe significant modifications of the flow; in this case, all the critical parameters are reduced, an effect that is more pronounced at small Ekman numbers. Beyond onset, we study the variations of the structure and properties of the magnetically-modified convective flows with increasing Rayleigh numbers. In particular, we note the weak relative kinetic helicity, the rapid breakdown of the columnarity, and the enhanced heat transport efficiency of the flows obtained for imposed field strengths of order one. Furthermore, magnetic and thermal winds drive a significant zonal flow in this case, which is not present with no imposed field or with stronger imposed fields. The mechanisms for magnetic field generation (particularly the lengthscales involved in the axisymmetric field production) vary with the strength of the imposed field, with three distinct regimes being observed for weak, order one, and stronger imposed fields. In the last two cases, the induced magnetic field reinforces the imposed field, even exceeding its strength for large Rayleigh numbers, which suggests that magnetically-modified flows might be able to produce large-scale self-sustained magnetic field. These magnetoconvection calculations are relevant to planets orbiting magnetically active hosts, and also help to elucidate the mechanisms for field generation in a strong-field regime.
{"title":"Magnetoconvection in a rotating spherical shell in the presence of a uniform axial magnetic field","authors":"Stephen J. Mason, C. Guervilly, G. Sarson","doi":"10.1080/03091929.2022.2107202","DOIUrl":"https://doi.org/10.1080/03091929.2022.2107202","url":null,"abstract":"ABSTRACT We report simulations of thermal convection and magnetic-field generation in a rapidly-rotating spherical shell, in the presence of a uniform axial magnetic field of variable strength. We consider the effect of the imposed field on the critical parameters (Rayleigh number, azimuthal wavenumber and propagation frequency) for the onset of convection, and on the relative importance of Coriolis, buoyancy and Lorentz forces in the resulting solutions. The imposed field strength must be of order one (corresponding to an Elsasser number of unity) to observe significant modifications of the flow; in this case, all the critical parameters are reduced, an effect that is more pronounced at small Ekman numbers. Beyond onset, we study the variations of the structure and properties of the magnetically-modified convective flows with increasing Rayleigh numbers. In particular, we note the weak relative kinetic helicity, the rapid breakdown of the columnarity, and the enhanced heat transport efficiency of the flows obtained for imposed field strengths of order one. Furthermore, magnetic and thermal winds drive a significant zonal flow in this case, which is not present with no imposed field or with stronger imposed fields. The mechanisms for magnetic field generation (particularly the lengthscales involved in the axisymmetric field production) vary with the strength of the imposed field, with three distinct regimes being observed for weak, order one, and stronger imposed fields. In the last two cases, the induced magnetic field reinforces the imposed field, even exceeding its strength for large Rayleigh numbers, which suggests that magnetically-modified flows might be able to produce large-scale self-sustained magnetic field. These magnetoconvection calculations are relevant to planets orbiting magnetically active hosts, and also help to elucidate the mechanisms for field generation in a strong-field regime.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"23 1","pages":"458 - 498"},"PeriodicalIF":1.3,"publicationDate":"2022-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84389004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-04DOI: 10.1080/03091929.2022.2098284
Long Chen
Multiplicity in optimal kinematic dynamos exists for certain types of symmetry classes and boundary conditions, at least near the lowest dynamo onset . Here we investigate the NNT type dynamo generated by steady flows with impermeable boundary conditions in a cube, where the letter N or T stands for pseudo-vacuum or superconducting boundary conditions along x, y, z directions, respectively. We find the top two of the three branches in the neighbourhood of have their growth rates crossed over at . Within each branch, the spatial structure of the optimal velocity field gradually shifts with respect to . At about above , the original optimal branch has developed distinct combinations of dominant Fourier modes. In contrast, the first suboptimal branch shows the least change in structure. We then follow the evolution of selected optimised solutions when varies until it becomes unstable. Specific modes in the flow that can destabilise the dynamo are identified. Within the range surveyed, we find that there can be one to two dynamo windows. All three branches generate a steady dynamo near , but the first suboptimal branch can generate an oscillatory dynamo at about eight times , and for both suboptimal branches, the growth rate reaches saturation approximately at . We find the two suboptimal branches create a more robust dynamo action supercritically.
在某些对称类和边界条件下，最优运动发电机存在多重性，至少在最低发电机起点附近存在多重性。在这里，我们研究了由立方体中具有不渗透边界条件的稳定流动产生的NNT型发电机，其中字母N或T分别代表沿x, y, z方向的伪真空或超导边界条件。我们发现在附近的三个分支中，最上面的两个的增长率相交于。在各支路内，最优速度场的空间结构相对于。大约在上面，原始的最优分支已经发展出不同的主要傅立叶模式组合。相比之下，第一个次优分支的结构变化最小。然后，当选择的优化解决方案发生变化时，我们遵循其演变，直到它变得不稳定。确定了流动中可能破坏发电机稳定的特定模式。在测量范围内，我们发现可以有一到两个发电机窗口。所有三个分支都在附近产生稳定的发电机，但第一个次优分支可以在大约8倍的时间内产生振荡发电机，并且对于两个次优分支，增长率大约达到饱和。我们发现两个次优分支超临界地创造了一个更鲁棒的发电机作用。
{"title":"Multiplicity in an optimised kinematic dynamo","authors":"Long Chen","doi":"10.1080/03091929.2022.2098284","DOIUrl":"https://doi.org/10.1080/03091929.2022.2098284","url":null,"abstract":"Multiplicity in optimal kinematic dynamos exists for certain types of symmetry classes and boundary conditions, at least near the lowest dynamo onset . Here we investigate the NNT type dynamo generated by steady flows with impermeable boundary conditions in a cube, where the letter N or T stands for pseudo-vacuum or superconducting boundary conditions along x, y, z directions, respectively. We find the top two of the three branches in the neighbourhood of have their growth rates crossed over at . Within each branch, the spatial structure of the optimal velocity field gradually shifts with respect to . At about above , the original optimal branch has developed distinct combinations of dominant Fourier modes. In contrast, the first suboptimal branch shows the least change in structure. We then follow the evolution of selected optimised solutions when varies until it becomes unstable. Specific modes in the flow that can destabilise the dynamo are identified. Within the range surveyed, we find that there can be one to two dynamo windows. All three branches generate a steady dynamo near , but the first suboptimal branch can generate an oscillatory dynamo at about eight times , and for both suboptimal branches, the growth rate reaches saturation approximately at . We find the two suboptimal branches create a more robust dynamo action supercritically.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"67 1","pages":"290 - 304"},"PeriodicalIF":1.3,"publicationDate":"2022-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85621201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-21DOI: 10.1080/03091929.2022.2085696
C. Prior, P. Wyper
Reconnection involving magnetic separators is known to lead to the spontaneous generation of new separator pairs. In this work, we explore the bifurcation process for a system composed of a pair of null points with a joining separator. We begin with a simplified analytical model to derive the basic principles of bifurcation in this system and then consider models with more general separator curve geometry and generic localised null structure. We demonstrate that the maximum pairwise linking (net-winding) of the separator and the local fan plane always approaches a multiple of 0.25 just before bifurcation. Additionally, we show the integrated twisting along the separator (the field strength normalised parallel current) can be used to determine when this limit will definitely lead to bifurcation. We present step-by-step algorithms to assess how close such systems are to bifurcation.
{"title":"An exact threshold for separator bifurcation","authors":"C. Prior, P. Wyper","doi":"10.1080/03091929.2022.2085696","DOIUrl":"https://doi.org/10.1080/03091929.2022.2085696","url":null,"abstract":"Reconnection involving magnetic separators is known to lead to the spontaneous generation of new separator pairs. In this work, we explore the bifurcation process for a system composed of a pair of null points with a joining separator. We begin with a simplified analytical model to derive the basic principles of bifurcation in this system and then consider models with more general separator curve geometry and generic localised null structure. We demonstrate that the maximum pairwise linking (net-winding) of the separator and the local fan plane always approaches a multiple of 0.25 just before bifurcation. Additionally, we show the integrated twisting along the separator (the field strength normalised parallel current) can be used to determine when this limit will definitely lead to bifurcation. We present step-by-step algorithms to assess how close such systems are to bifurcation.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"133 1","pages":"321 - 349"},"PeriodicalIF":1.3,"publicationDate":"2022-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86821039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-13DOI: 10.1080/03091929.2022.2060964
D. Faraco, Sauli Lindberg
We review recent mathematical results on the theory of ideal MHD turbulence. On the one hand, we explain a mathematical version of Taylor's conjecture on magnetic helicity conservation, both for simply and multiply connected domains. On the other hand, we describe how to prove the existence of weak solutions conserving magnetic helicity but dissipating cross helicity and energy in 3D Ideal MHD. Such solutions are bounded. In fact, we show that as soon as we are below the critical integrability for magnetic helicity conservation, there are weak solutions which do not preserve even magnetic helicity. These mathematical theorems rely on understanding the mathematical relaxation of MHD which is used as a model of the macroscopic behaviour of solutions of various nonlinear partial differential equations. Thus, on the one hand, we present results on the existence of weak solutions consistent with what is expected from experiments and numerical simulations, on the other hand, we show that below certain thresholds, there exist pathological solutions which should be excluded from physical grounds. It is still an outstanding open problem to find suitable admissibility conditions that are flexible enough to allow the existence of weak solutions but rigid enough to rule out physically unrealistic behaviour.
{"title":"Rigorous results on conserved and dissipated quantities in ideal MHD turbulence","authors":"D. Faraco, Sauli Lindberg","doi":"10.1080/03091929.2022.2060964","DOIUrl":"https://doi.org/10.1080/03091929.2022.2060964","url":null,"abstract":"We review recent mathematical results on the theory of ideal MHD turbulence. On the one hand, we explain a mathematical version of Taylor's conjecture on magnetic helicity conservation, both for simply and multiply connected domains. On the other hand, we describe how to prove the existence of weak solutions conserving magnetic helicity but dissipating cross helicity and energy in 3D Ideal MHD. Such solutions are bounded. In fact, we show that as soon as we are below the critical integrability for magnetic helicity conservation, there are weak solutions which do not preserve even magnetic helicity. These mathematical theorems rely on understanding the mathematical relaxation of MHD which is used as a model of the macroscopic behaviour of solutions of various nonlinear partial differential equations. Thus, on the one hand, we present results on the existence of weak solutions consistent with what is expected from experiments and numerical simulations, on the other hand, we show that below certain thresholds, there exist pathological solutions which should be excluded from physical grounds. It is still an outstanding open problem to find suitable admissibility conditions that are flexible enough to allow the existence of weak solutions but rigid enough to rule out physically unrealistic behaviour.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"1 1","pages":"237 - 260"},"PeriodicalIF":1.3,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84552240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-25DOI: 10.1080/03091929.2022.2074983
Erwan Oulhen, J. Reinaud, X. Carton
The merger of two surface quasi-geostrophic vortices is examined in detail. As the two vortices collapse towards each other in the merging process, they trap their external fronts between them; these fronts are inserted into the final merged vortex, where they form a central, nearly parallel, sheared velocity strip, sensitive to barotropic instability. As a result, this strip breaks up into an alley of small vortices. Subsequently, these small vortices may undergo merger and grow in size in the core of the large merged vortex. The number of small trapped vortices decreases correspondingly. Finally, a single or two small vortices remain. These processes are analysed using a numerical model of the surface quasi-geostrophic equations. The sensitivity of this process to the initial vortex characteristics is explored. A parallel is drawn between this problem and the instability of a rectilinear strip of temperature with a central gap. The application of this problem to the Ocean is discussed.
{"title":"Formation of small-scale vortices in the core of a large merged vortex","authors":"Erwan Oulhen, J. Reinaud, X. Carton","doi":"10.1080/03091929.2022.2074983","DOIUrl":"https://doi.org/10.1080/03091929.2022.2074983","url":null,"abstract":"The merger of two surface quasi-geostrophic vortices is examined in detail. As the two vortices collapse towards each other in the merging process, they trap their external fronts between them; these fronts are inserted into the final merged vortex, where they form a central, nearly parallel, sheared velocity strip, sensitive to barotropic instability. As a result, this strip breaks up into an alley of small vortices. Subsequently, these small vortices may undergo merger and grow in size in the core of the large merged vortex. The number of small trapped vortices decreases correspondingly. Finally, a single or two small vortices remain. These processes are analysed using a numerical model of the surface quasi-geostrophic equations. The sensitivity of this process to the initial vortex characteristics is explored. A parallel is drawn between this problem and the instability of a rectilinear strip of temperature with a central gap. The application of this problem to the Ocean is discussed.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"17 1","pages":"411 - 432"},"PeriodicalIF":1.3,"publicationDate":"2022-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84789051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-04DOI: 10.1080/03091929.2022.2065271
L. Zavala Sansón
This paper studies the effects of time-dependent, mesoscale turbulence on the wind-driven ocean circulation in a closed basin with variable topography. Numerical simulations of a single-layer fluid with finite topography at the sloping boundaries are performed. The flow is forced by a suitable combination of a steady, basin-scale wind that generates the classical western-intensified anticyclonic gyre, plus a shorter, time-dependent forcing that injects energy at a narrow range of scales. Two contrasting situations are considered. First, in the absence of the large-scale forcing, the turbulence generates a cyclonic flow that follows the geostrophic contours around the basin. Second, the resulting mean circulation is studied when the large and small-scale forcing terms are considered together. In particular, it is discussed that the alteration of the anticyclonic gyre may be due to the turbulent-induced cyclonic circulation.
{"title":"Effects of mesoscale turbulence on the wind-driven circulation in a closed basin with topography","authors":"L. Zavala Sansón","doi":"10.1080/03091929.2022.2065271","DOIUrl":"https://doi.org/10.1080/03091929.2022.2065271","url":null,"abstract":"This paper studies the effects of time-dependent, mesoscale turbulence on the wind-driven ocean circulation in a closed basin with variable topography. Numerical simulations of a single-layer fluid with finite topography at the sloping boundaries are performed. The flow is forced by a suitable combination of a steady, basin-scale wind that generates the classical western-intensified anticyclonic gyre, plus a shorter, time-dependent forcing that injects energy at a narrow range of scales. Two contrasting situations are considered. First, in the absence of the large-scale forcing, the turbulence generates a cyclonic flow that follows the geostrophic contours around the basin. Second, the resulting mean circulation is studied when the large and small-scale forcing terms are considered together. In particular, it is discussed that the alteration of the anticyclonic gyre may be due to the turbulent-induced cyclonic circulation.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"191 1","pages":"159 - 184"},"PeriodicalIF":1.3,"publicationDate":"2022-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78990669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-04DOI: 10.1080/03091929.2022.2066659
A. Evgrafova, A. Sukhanovskii
ABSTRACT Numerical simulations of a laboratory model of a tropical cyclone are carried out for different rotation rates. Particular attention is paid to the non-stationary stage of intensive cyclonic vortex formation. The transfer of angular momentum plays a key role in the formation of cyclonic and anticyclonic flows; therefore, a detailed analysis of the redistribution and variation of angular momentum is given. The time evolution of angular momentum fluxes and total angular momentum strongly depend on the rotation rate. It is shown that intensive cyclonic motion with velocity exceeding initial values substantially (ten or more times) is a result of accumulation in the centre of a small fraction of global angular momentum of a fluid layer (from 0.25% at fast rotation to 2% at slow rotation). The integral angular momentum of the anticyclonic flow is significantly larger than that of the cyclonic flow, mainly because of the relatively large fluid volume of the anticyclonic flow. Another important result is that the rotating fluid layer very quickly adapts to new boundary conditions (heating and cooling). Approximately two rotation periods are required to reach a quasi-stationary state. The application of the obtained results to the evolution of real tropical cyclones is discussed.
{"title":"Angular momentum transfer in direct numerical simulations of a laboratory model of a tropical cyclone","authors":"A. Evgrafova, A. Sukhanovskii","doi":"10.1080/03091929.2022.2066659","DOIUrl":"https://doi.org/10.1080/03091929.2022.2066659","url":null,"abstract":"ABSTRACT Numerical simulations of a laboratory model of a tropical cyclone are carried out for different rotation rates. Particular attention is paid to the non-stationary stage of intensive cyclonic vortex formation. The transfer of angular momentum plays a key role in the formation of cyclonic and anticyclonic flows; therefore, a detailed analysis of the redistribution and variation of angular momentum is given. The time evolution of angular momentum fluxes and total angular momentum strongly depend on the rotation rate. It is shown that intensive cyclonic motion with velocity exceeding initial values substantially (ten or more times) is a result of accumulation in the centre of a small fraction of global angular momentum of a fluid layer (from 0.25% at fast rotation to 2% at slow rotation). The integral angular momentum of the anticyclonic flow is significantly larger than that of the cyclonic flow, mainly because of the relatively large fluid volume of the anticyclonic flow. Another important result is that the rotating fluid layer very quickly adapts to new boundary conditions (heating and cooling). Approximately two rotation periods are required to reach a quasi-stationary state. The application of the obtained results to the evolution of real tropical cyclones is discussed.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"22 1","pages":"185 - 205"},"PeriodicalIF":1.3,"publicationDate":"2022-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83298009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-04DOI: 10.1080/03091929.2022.2036337
A. Constantin
ABSTRACT We clarify and correct an oversight from a recent paper, thus confirming the possibility of a nonlinear coupling of inertial oscillations and Ekman-type spiralling wind-drift currents to yield an exact solution of the system describing the leading-order dynamics of wind-drift arctic flows.
{"title":"Comments on: nonlinear wind-drift ocean currents in arctic regions","authors":"A. Constantin","doi":"10.1080/03091929.2022.2036337","DOIUrl":"https://doi.org/10.1080/03091929.2022.2036337","url":null,"abstract":"ABSTRACT We clarify and correct an oversight from a recent paper, thus confirming the possibility of a nonlinear coupling of inertial oscillations and Ekman-type spiralling wind-drift currents to yield an exact solution of the system describing the leading-order dynamics of wind-drift arctic flows.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"49 1","pages":"116 - 121"},"PeriodicalIF":1.3,"publicationDate":"2022-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86728400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-07DOI: 10.1080/03091929.2022.2025792
Ayan Chanda, S. Bora
A hydroelastic model is presented here to look into the scattering of oblique water waves by two totally submerged vertical porous plates, placed at some distance from each other, in a homogeneous fluid flowing over an elastic sea-floor. Consideration of Euler–Bernoulli beam equation allows the elastic sea-floor to be approximated as a thin elastic plate whereas the porous plates follow the porous wave-maker theory. The complete analytical solution, under the assumption of small-amplitude theory and structural response, is obtained by employing eigenfunction expansion and least square method. Subsequently, numerical computation for the reflection and transmission coefficients and energy loss are carried out and discussed for different values of the elasticity of the sea-floor, porosity of the porous plates and other structural parameters. The present study establishes that reflection of the waves exhibits an oscillatory behaviour. It further shows that, due to an increase in the inertial effect of the porous plate, the minima in wave reflection occurs. The vertical porous plates are found to dissipate a significant portion of the wave energy when an increase in the inertial effect of the porous plates takes place. Furthermore, wave transmission decreases significantly due to the energy dissipation by the elastic sea-floor. Significant variation in the elastic specification of the sea-floor commands considerable influence when the propagating wave impinges upon the submerged vertical porous plates. In order to validate the present model, the obtained results are compared with available results which points towards a good agreement.
{"title":"Different approaches in scattering of water waves by two submerged porous plates over an elastic sea-floor","authors":"Ayan Chanda, S. Bora","doi":"10.1080/03091929.2022.2025792","DOIUrl":"https://doi.org/10.1080/03091929.2022.2025792","url":null,"abstract":"A hydroelastic model is presented here to look into the scattering of oblique water waves by two totally submerged vertical porous plates, placed at some distance from each other, in a homogeneous fluid flowing over an elastic sea-floor. Consideration of Euler–Bernoulli beam equation allows the elastic sea-floor to be approximated as a thin elastic plate whereas the porous plates follow the porous wave-maker theory. The complete analytical solution, under the assumption of small-amplitude theory and structural response, is obtained by employing eigenfunction expansion and least square method. Subsequently, numerical computation for the reflection and transmission coefficients and energy loss are carried out and discussed for different values of the elasticity of the sea-floor, porosity of the porous plates and other structural parameters. The present study establishes that reflection of the waves exhibits an oscillatory behaviour. It further shows that, due to an increase in the inertial effect of the porous plate, the minima in wave reflection occurs. The vertical porous plates are found to dissipate a significant portion of the wave energy when an increase in the inertial effect of the porous plates takes place. Furthermore, wave transmission decreases significantly due to the energy dissipation by the elastic sea-floor. Significant variation in the elastic specification of the sea-floor commands considerable influence when the propagating wave impinges upon the submerged vertical porous plates. In order to validate the present model, the obtained results are compared with available results which points towards a good agreement.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"98 1","pages":"206 - 233"},"PeriodicalIF":1.3,"publicationDate":"2022-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86049219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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