Pub Date : 2022-11-26DOI: 10.1080/10618562.2023.2237898
Xiaogang Li, Tian Xia, Yuxi Deng, Siqi Yang, Yonbin Ge
In this work, a new, improved third-order finite difference weighted essentially non-oscillatory scheme is presented for one- and two-dimensional hyperbolic conservation laws and associated problems. The parameter p which is regulate dissipation is introduced in the nonlinear weights in the framework of the conventional WENO-Z scheme, and the higher-order global smoothness indicator is obtained by the idea of Wang [Wang, Y. H., Y. L. Du, K. L. Zhao and L. Yuan. 2020. ‘A Low-dissipation Third-order Weighted Essentially Nonoscillatory Scheme with a New Reference Smoothness Indicator’. International Journal for Numerical Methods in Fluids. 92 (9): 1212–1234.], the sufficient condition of nonlinear weights is proved by using Taylor expansions. Finally, the value range of parameter p is obtained. The proposed scheme is verified to achieve the optimal order near critical points by linear convection equations with different initial values, and the high-resolution characteristic of the present scheme is proved on a variety of one- and two- dimensional standard numerical examples. Numerical results demonstrate that the proposed scheme gives better performance in comparison with the other third-order WENO schemes.
在这项工作中，提出了一种新的改进的三阶有限差分加权本质非振荡格式，用于一维和二维双曲守恒律和相关问题。在传统WENO-Z格式框架的非线性权值中引入了调节耗散参数p，并采用Wang的思想得到了高阶全局平滑指标[j] . Wang, yyh .， Du yl .， Zhao kl .， Yuan L. 2020。一种具有新的参考平滑指标的低耗散三阶加权基本非振荡格式。流体力学与工程学报，2009(9):1212-1234。]，用泰勒展开式证明了非线性权值存在的充分条件。最后得到参数p的取值范围。通过不同初值的线性对流方程，验证了该格式在临界点附近的最优阶，并在各种一维和二维标准数值算例上证明了该格式的高分辨率特性。数值结果表明，与其他三阶WENO算法相比，该算法具有更好的性能。
{"title":"A New Third-Order Finite Difference WENO Scheme to Improve Convergence Rate at Critical Points","authors":"Xiaogang Li, Tian Xia, Yuxi Deng, Siqi Yang, Yonbin Ge","doi":"10.1080/10618562.2023.2237898","DOIUrl":"https://doi.org/10.1080/10618562.2023.2237898","url":null,"abstract":"In this work, a new, improved third-order finite difference weighted essentially non-oscillatory scheme is presented for one- and two-dimensional hyperbolic conservation laws and associated problems. The parameter p which is regulate dissipation is introduced in the nonlinear weights in the framework of the conventional WENO-Z scheme, and the higher-order global smoothness indicator is obtained by the idea of Wang [Wang, Y. H., Y. L. Du, K. L. Zhao and L. Yuan. 2020. ‘A Low-dissipation Third-order Weighted Essentially Nonoscillatory Scheme with a New Reference Smoothness Indicator’. International Journal for Numerical Methods in Fluids. 92 (9): 1212–1234.], the sufficient condition of nonlinear weights is proved by using Taylor expansions. Finally, the value range of parameter p is obtained. The proposed scheme is verified to achieve the optimal order near critical points by linear convection equations with different initial values, and the high-resolution characteristic of the present scheme is proved on a variety of one- and two- dimensional standard numerical examples. Numerical results demonstrate that the proposed scheme gives better performance in comparison with the other third-order WENO schemes.","PeriodicalId":56288,"journal":{"name":"International Journal of Computational Fluid Dynamics","volume":"178 1","pages":"857 - 874"},"PeriodicalIF":1.3,"publicationDate":"2022-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80247655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-26DOI: 10.1080/10618562.2023.2229250
N. Pham-Sy, C. Tran
A non-overlapping domain decomposition-based parallel algorithm coupled with a compact local integrated radial basis function (CLIRBF) method is developed for solving Navier-Stokes equations. For this approach, a problem is divided into subdomains. In each sub-domain, a CLIRBF scheme is applied to solve the Navier-Stokes equations of flows. A relaxation factor is used at the interface between sub-domains to ensure the quick convergence of the present method. The Bitmap termination detection technique is introduced to complete the global termination. The present approach is verified using two fluid flow problems: the lid-driven cavity and the natural convection in concentric annuli flow. The numerical results have demonstrated the efficiency of the present parallel method compared with the corresponding sequential one and other published methods. Especially, super-linear speed-up was achieved for several CPUs. In terms of accuracy, the obtained results are in very good agreement with benchmark results.
{"title":"Parallel Computation Using Non-Overlapping Domain Decomposition Coupled with Compact Local Integrated RBF for Navier–Stokes Equations","authors":"N. Pham-Sy, C. Tran","doi":"10.1080/10618562.2023.2229250","DOIUrl":"https://doi.org/10.1080/10618562.2023.2229250","url":null,"abstract":"A non-overlapping domain decomposition-based parallel algorithm coupled with a compact local integrated radial basis function (CLIRBF) method is developed for solving Navier-Stokes equations. For this approach, a problem is divided into subdomains. In each sub-domain, a CLIRBF scheme is applied to solve the Navier-Stokes equations of flows. A relaxation factor is used at the interface between sub-domains to ensure the quick convergence of the present method. The Bitmap termination detection technique is introduced to complete the global termination. The present approach is verified using two fluid flow problems: the lid-driven cavity and the natural convection in concentric annuli flow. The numerical results have demonstrated the efficiency of the present parallel method compared with the corresponding sequential one and other published methods. Especially, super-linear speed-up was achieved for several CPUs. In terms of accuracy, the obtained results are in very good agreement with benchmark results.","PeriodicalId":56288,"journal":{"name":"International Journal of Computational Fluid Dynamics","volume":"20 1","pages":"835 - 856"},"PeriodicalIF":1.3,"publicationDate":"2022-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91306707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-21DOI: 10.1080/10618562.2023.2189704
G. Zhao, Chengwen Zhong, Sha Liu, Yong Wang, Congshan Zhuo
A gas-kinetic scheme (GKS) with kinetic boundary condition based on unstructured mesh is present here. In the GKS method, the solid wall boundary conditions can be constructed by virtue of the gas distribution function, which is similar to the diffuse-scattering rule used in the other kinetic schemes. The kinetic boundary condition has a concise form and easy to implement. The use of unstructured mesh expands the adaptability of GKS to simulate the flows with complex geometry. The kinetic boundary condition can recover to the non-slip boundary condition in the continuum regime. In the slip regime, the slip velocity can be accurately predicted by kinetic boundary condition, which turns into the slip boundary condition. The use of kinetic boundary condition improves the calculation results of GKS in near-continuum flow. A series of test cases, from incompressible to compressible flow with a wide range of Knudsen number, are investigated to demonstrate the performance of kinetic boundary condition in near-continuum flow, which can provide a reference for the construction and optimisation for GKS-based multi-scale hybrid algorithms.
{"title":"Application of Gas-Kinetic Scheme for Continuum and Near-Continuum Flow on Unstructured Mesh","authors":"G. Zhao, Chengwen Zhong, Sha Liu, Yong Wang, Congshan Zhuo","doi":"10.1080/10618562.2023.2189704","DOIUrl":"https://doi.org/10.1080/10618562.2023.2189704","url":null,"abstract":"A gas-kinetic scheme (GKS) with kinetic boundary condition based on unstructured mesh is present here. In the GKS method, the solid wall boundary conditions can be constructed by virtue of the gas distribution function, which is similar to the diffuse-scattering rule used in the other kinetic schemes. The kinetic boundary condition has a concise form and easy to implement. The use of unstructured mesh expands the adaptability of GKS to simulate the flows with complex geometry. The kinetic boundary condition can recover to the non-slip boundary condition in the continuum regime. In the slip regime, the slip velocity can be accurately predicted by kinetic boundary condition, which turns into the slip boundary condition. The use of kinetic boundary condition improves the calculation results of GKS in near-continuum flow. A series of test cases, from incompressible to compressible flow with a wide range of Knudsen number, are investigated to demonstrate the performance of kinetic boundary condition in near-continuum flow, which can provide a reference for the construction and optimisation for GKS-based multi-scale hybrid algorithms.","PeriodicalId":56288,"journal":{"name":"International Journal of Computational Fluid Dynamics","volume":"12 1","pages":"753 - 775"},"PeriodicalIF":1.3,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76193943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-21DOI: 10.1080/10618562.2023.2189247
D. J. Lusher, G. Coleman
ABSTRACT Direct numerical simulation is used to determine the turbulent Prandtl number above cold (isothermal) and hot (adiabatic) walls in a family of low-supersonic channel flows. A range of mean temperature/density variations, corresponding to effective/edge Mach numbers between 1.1 to 2.2, and wall-variable-based Reynolds number from 73 to 3800, is considered. The adiabatic condition is a new feature of special interest. The value of away from the wall approaches 0.85 above both the isothermal and adiabatic walls. The variations of the near-wall profiles in both the present and previous, passive-scalar simulations collapse as a function of the semilocal wall scaling proposed in 1995 by [Huang, P. G., G. N. Coleman, and P. Bradshaw. 1995. “Compressible Turbulent Channel Flows: DNS Results and Modelling.” Journal of Fluid Mechanics 305: 185–218. doi:10.1017/S0022112095004599.], with only a weak dependence on . This leads to a rather simple proposal for a model of heat transfer, attached to an eddy-viscosity model.
摘要采用直接数值模拟方法确定了一类低声速通道中冷(等温)壁面和热(绝热)壁面上的湍流普朗特数。考虑了一个平均温度/密度变化范围，对应于有效/边缘马赫数在1.1到2.2之间，基于壁面变量的雷诺数在73到3800之间。绝热条件是一个特别有趣的新特征。在等温壁面和绝热壁面以上，离壁面的差值均接近0.85。[Huang, P. G. Coleman, and P. Bradshaw. 1995]在1995年提出的被动标量模拟中，近壁面剖面的变化作为半局部壁面结垢的函数而崩溃。可压缩湍流通道流动:DNS结果和建模。流体力学学报(自然科学版);doi: 10.1017 / S0022112095004599。对…只有微弱的依赖。这导致了一个相当简单的传热模型的提议，附属于涡流粘度模型。
{"title":"Numerical Study of Compressible Wall-Bounded Turbulence – the Effect of Thermal Wall Conditions on the Turbulent Prandtl Number in the Low-Supersonic Regime","authors":"D. J. Lusher, G. Coleman","doi":"10.1080/10618562.2023.2189247","DOIUrl":"https://doi.org/10.1080/10618562.2023.2189247","url":null,"abstract":"ABSTRACT Direct numerical simulation is used to determine the turbulent Prandtl number above cold (isothermal) and hot (adiabatic) walls in a family of low-supersonic channel flows. A range of mean temperature/density variations, corresponding to effective/edge Mach numbers between 1.1 to 2.2, and wall-variable-based Reynolds number from 73 to 3800, is considered. The adiabatic condition is a new feature of special interest. The value of away from the wall approaches 0.85 above both the isothermal and adiabatic walls. The variations of the near-wall profiles in both the present and previous, passive-scalar simulations collapse as a function of the semilocal wall scaling proposed in 1995 by [Huang, P. G., G. N. Coleman, and P. Bradshaw. 1995. “Compressible Turbulent Channel Flows: DNS Results and Modelling.” Journal of Fluid Mechanics 305: 185–218. doi:10.1017/S0022112095004599.], with only a weak dependence on . This leads to a rather simple proposal for a model of heat transfer, attached to an eddy-viscosity model.","PeriodicalId":56288,"journal":{"name":"International Journal of Computational Fluid Dynamics","volume":"1 1","pages":"797 - 815"},"PeriodicalIF":1.3,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88663788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-21DOI: 10.1080/10618562.2023.2202391
Kai Yang, T. Aoki
A consistent and conservative formulation for mass and momentum transport is proposed in the context of simulating incompressible two-phase flows by using weakly compressible method. Combined with the evolving pressure projection method to prevent oscillation of the solution induced by the acoustic wave, this solver aims at a robust and accurate computation of violent two-phase flows with a high density ratio, while taking advantage of fully explicit time integration of the weakly compressible Navier–Stokes equations. Coupled with the volume of fluid method for capturing interfaces, the mass and momentum fluxes are evaluated in a consistent manner using the finite volume method. In addition, a special implementation of the pressure projection is devised to avoid velocity-pressure decoupling on a collocated grid. The solver's accuracy and stability are demonstrated through various two-phase flow simulations, including dam break and liquid jet atomization scenarios, emphasizing its momentum-conserving properties.
{"title":"A Momentum-Conserving Weakly Compressible Navier–Stokes Solver for Simulation of Violent Two-Phase Flows with High Density Ratio","authors":"Kai Yang, T. Aoki","doi":"10.1080/10618562.2023.2202391","DOIUrl":"https://doi.org/10.1080/10618562.2023.2202391","url":null,"abstract":"A consistent and conservative formulation for mass and momentum transport is proposed in the context of simulating incompressible two-phase flows by using weakly compressible method. Combined with the evolving pressure projection method to prevent oscillation of the solution induced by the acoustic wave, this solver aims at a robust and accurate computation of violent two-phase flows with a high density ratio, while taking advantage of fully explicit time integration of the weakly compressible Navier–Stokes equations. Coupled with the volume of fluid method for capturing interfaces, the mass and momentum fluxes are evaluated in a consistent manner using the finite volume method. In addition, a special implementation of the pressure projection is devised to avoid velocity-pressure decoupling on a collocated grid. The solver's accuracy and stability are demonstrated through various two-phase flow simulations, including dam break and liquid jet atomization scenarios, emphasizing its momentum-conserving properties.","PeriodicalId":56288,"journal":{"name":"International Journal of Computational Fluid Dynamics","volume":"28 1","pages":"776 - 796"},"PeriodicalIF":1.3,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88643613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-21DOI: 10.1080/10618562.2023.2192035
Guodong Zhu, Y. Wang, Jianhui Liu, Ji Zhou, Zhenghu Mo
We propose a new digital evaluation model for the negative-pressure molding mechanism, which is used to verify the feasibility of improvement measures for quality problem of the pad. The gas–solid flow in the negative pressure molding system facing the pad of diapers at the molding surface under different outlet pressures is studied using CFD-DEM bidirectional coupling simulation method. Aiming at the concentration of velocity/pressure values in the molding defect region, the uniformity coefficient is used as an important evaluation index to reflect the molding quality, and the parameters are optimised for the velocity and pressure uniformity of the gas phase in the molding defect region. For the fine flocculent discrete element, the parameter calibration is carried out, and the percentage of solid phase bearing at the screen is used as a reference index to further verify the feasibility of the improvement scheme. Finally, the model is applied to an improvement example, the results show that the molding defects of the cotton core layer are related to the velocity distribution of the molding surface. The molding quality can be significantly improved by setting a retaining ring at the outlet of the wind barn. The speed uniformity coefficient is improved by 44.2% when the retaining ring thickness s = 140 mm, inner diameter d = 1000 mm, and the relative position l = 0 mm. The molding quality has been significantly improved.
{"title":"Evaluation Method for the Reasonableness of Countermeasures for Defective Products in the Negative-Pressure Molding Mechanism","authors":"Guodong Zhu, Y. Wang, Jianhui Liu, Ji Zhou, Zhenghu Mo","doi":"10.1080/10618562.2023.2192035","DOIUrl":"https://doi.org/10.1080/10618562.2023.2192035","url":null,"abstract":"We propose a new digital evaluation model for the negative-pressure molding mechanism, which is used to verify the feasibility of improvement measures for quality problem of the pad. The gas–solid flow in the negative pressure molding system facing the pad of diapers at the molding surface under different outlet pressures is studied using CFD-DEM bidirectional coupling simulation method. Aiming at the concentration of velocity/pressure values in the molding defect region, the uniformity coefficient is used as an important evaluation index to reflect the molding quality, and the parameters are optimised for the velocity and pressure uniformity of the gas phase in the molding defect region. For the fine flocculent discrete element, the parameter calibration is carried out, and the percentage of solid phase bearing at the screen is used as a reference index to further verify the feasibility of the improvement scheme. Finally, the model is applied to an improvement example, the results show that the molding defects of the cotton core layer are related to the velocity distribution of the molding surface. The molding quality can be significantly improved by setting a retaining ring at the outlet of the wind barn. The speed uniformity coefficient is improved by 44.2% when the retaining ring thickness s = 140 mm, inner diameter d = 1000 mm, and the relative position l = 0 mm. The molding quality has been significantly improved.","PeriodicalId":56288,"journal":{"name":"International Journal of Computational Fluid Dynamics","volume":"86 18 1","pages":"816 - 833"},"PeriodicalIF":1.3,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84013943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-14DOI: 10.1080/10618562.2022.2164276
Y. Chandukrishna, T. N. Venkatesh
Traditional CFD techniques are not effective in preserving wakes and vortices over larger distances and for longer times. Vorticity Confinement (VC) technique helps counter the numerical diffusion to preserve wakes and vortices. In the current study, VC was used to accurately model the propeller flow using two different propeller modelling techniques after being implemented into SU2, an open-source CFD solver. One resolves flow past the propeller by solving RANS equations in a rotating reference frame. Another is a simplified propeller modelling technique in which the propeller needs to be modelled as a disk, and the propeller loading is determined using the blade element method. In the first case, VC enabled tip and hub vortices to convect over larger distances from the propeller, along with an improved resolution of gradients in the tip vortex. With the latter technique, VC helped conserve the tangential velocities for longer distances.
{"title":"Vorticity Confinement Technique and Blade Element Method for Accurate Propeller Modelling","authors":"Y. Chandukrishna, T. N. Venkatesh","doi":"10.1080/10618562.2022.2164276","DOIUrl":"https://doi.org/10.1080/10618562.2022.2164276","url":null,"abstract":"Traditional CFD techniques are not effective in preserving wakes and vortices over larger distances and for longer times. Vorticity Confinement (VC) technique helps counter the numerical diffusion to preserve wakes and vortices. In the current study, VC was used to accurately model the propeller flow using two different propeller modelling techniques after being implemented into SU2, an open-source CFD solver. One resolves flow past the propeller by solving RANS equations in a rotating reference frame. Another is a simplified propeller modelling technique in which the propeller needs to be modelled as a disk, and the propeller loading is determined using the blade element method. In the first case, VC enabled tip and hub vortices to convect over larger distances from the propeller, along with an improved resolution of gradients in the tip vortex. With the latter technique, VC helped conserve the tangential velocities for longer distances.","PeriodicalId":56288,"journal":{"name":"International Journal of Computational Fluid Dynamics","volume":"211 1","pages":"719 - 730"},"PeriodicalIF":1.3,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76971194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-14DOI: 10.1080/10618562.2023.2187050
Zhihui Li, R. Agarwal
The unsteady simulations are conducted, and the computed results with WA model are compared with the experimental data in conjunction with the simulation results obtained using traditional models. It is shown that on the mid-span sections of the cascade airfoils the distributions of near-wall static pressure coefficients from each turbulence model agree well with the experimental data. On the lower spanwise sections, the discrepancy between the numerical simulations and experimental data generally increases. Among the three turbulence models, the WA turbulence model shows better agreement with the experimental data in predicting the spanwise total pressure losses downstream of the cascade blade. The WA model is then embedded into the adjoint optimisation loop to test its capability in minimising the flow losses in the compressor cascade passage. The optimisation results show that the total pressure loss coefficient of the optimised compressor cascade is reduced by 18.1% compared to the baseline design.
{"title":"Numerical Simulations and Design Optimization of Compressor Cascade Flow Using One Equation and Wray-Agarwal Turbulence Model","authors":"Zhihui Li, R. Agarwal","doi":"10.1080/10618562.2023.2187050","DOIUrl":"https://doi.org/10.1080/10618562.2023.2187050","url":null,"abstract":"The unsteady simulations are conducted, and the computed results with WA model are compared with the experimental data in conjunction with the simulation results obtained using traditional models. It is shown that on the mid-span sections of the cascade airfoils the distributions of near-wall static pressure coefficients from each turbulence model agree well with the experimental data. On the lower spanwise sections, the discrepancy between the numerical simulations and experimental data generally increases. Among the three turbulence models, the WA turbulence model shows better agreement with the experimental data in predicting the spanwise total pressure losses downstream of the cascade blade. The WA model is then embedded into the adjoint optimisation loop to test its capability in minimising the flow losses in the compressor cascade passage. The optimisation results show that the total pressure loss coefficient of the optimised compressor cascade is reduced by 18.1% compared to the baseline design.","PeriodicalId":56288,"journal":{"name":"International Journal of Computational Fluid Dynamics","volume":"41 1","pages":"705 - 718"},"PeriodicalIF":1.3,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85321104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-14DOI: 10.1080/10618562.2022.2162892
Zi-Qiao Wei, J. Li, Songxiang Tang
The flow past a simplified wing-body junction configuration is simulated using a shear layer adaptive improved delayed detached-eddy-simulation (SLA-IDDES) approach in which an appropriate subgrid lengthscale is adopted in the boundary region, where the grid may be strongly anisotropic, to prevent the excessive generation of subgrid-scale eddy viscosity. The numerical results show overall good agreement with the experiment carried out by Ölçmen and Simpson. The self-induced chaotic switching of the horseshoe vortex between two flow modes is simulated and analysed, and its effects on the vortex legs and their inherent oscillation are also investigated. It is found that the corner vortex also exhibits an alternating formation and breakdown process with basically the same frequency as the horseshoe vortex. Corner separation is found to be affected also by the upstream horseshoe vortex and the inherent oscillation of the vortex legs.
{"title":"Numerical Investigation of a Simplified Wing–body Junction Flow","authors":"Zi-Qiao Wei, J. Li, Songxiang Tang","doi":"10.1080/10618562.2022.2162892","DOIUrl":"https://doi.org/10.1080/10618562.2022.2162892","url":null,"abstract":"The flow past a simplified wing-body junction configuration is simulated using a shear layer adaptive improved delayed detached-eddy-simulation (SLA-IDDES) approach in which an appropriate subgrid lengthscale is adopted in the boundary region, where the grid may be strongly anisotropic, to prevent the excessive generation of subgrid-scale eddy viscosity. The numerical results show overall good agreement with the experiment carried out by Ölçmen and Simpson. The self-induced chaotic switching of the horseshoe vortex between two flow modes is simulated and analysed, and its effects on the vortex legs and their inherent oscillation are also investigated. It is found that the corner vortex also exhibits an alternating formation and breakdown process with basically the same frequency as the horseshoe vortex. Corner separation is found to be affected also by the upstream horseshoe vortex and the inherent oscillation of the vortex legs.","PeriodicalId":56288,"journal":{"name":"International Journal of Computational Fluid Dynamics","volume":"22 1","pages":"731 - 751"},"PeriodicalIF":1.3,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84719372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-14DOI: 10.1080/10618562.2023.2176487
Matteo Ugolotti, P. Orkwis, Nathan A. Wukie
The adjoint method has been extensively used in many areas of CFD such as gradient-based shape optimisation. When utilising the RANS equations for simulating turbulent flows, the adjoint method requires a scrupulous differentiation of the RANS equations, including the wall distance contribution. This can be a challenging task and a potential source of inaccuracy for functional sensitivities if not correctly executed. This paper presents a formulation for including the contribution of an equation-based wall distance model to the discrete adjoint of a RANS model. The proposed formulation is tested in a gradient-based optimisation scenario and the effects of the wall distance adjoint fields on the functional sensitivities are investigated. Neglecting the contribution of the wall distance adjoint yields an error in the functional sensitivities with respect to volume mesh nodes. Including the wall distance adjoint restores the accuracy of the functional sensitivities yielding better convergence of the design optimisation.
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