Understanding the dynamics and inherent mechanisms of sphere impact on suspended films is important for improving sphere-film separation techniques. In this study, we conducted experiments to investigate the dynamics of sphere impact on suspended films and examine typical phenomena. We revealed the effects of dynamic viscosity and surface tension of films by altering the glycerol content (G) and the relative surfactant concentration (C*) and elucidated the characteristics of film deformation, sphere trajectory (hs), and contact time (tc). Moreover, we obtained the influences of sphere and film properties on bubble volume (Vbub) by analyzing force balance. The results indicate that three modes are observed and divided using the dimensionless energy parameter E* = Ek0/(ΔEfs + Evis) based on energy analysis, considering the sphere kinetic energy (Ek0), film surface energy increment (ΔEfs), and viscous dissipation (Evis): satisfying E* < 1, retention occurs; satisfying 1 < E* < 127.7(Ds/Df)2 (where Ds is the sphere diameter, Df is the film diameter), bubble entrainment passing appears; satisfying E* > 127.7(Ds/Df)2, non-bubble entrainment passing emerges. During retention, increasing G and C* causes film surface elasticity and hs to present a trend of first rising and then falling. For passing, the increase in G reduces deformability, leading hs to decrease, while increasing C* makes the film more susceptible to deformation, causing hs to increase. In addition, a film vibration period (τf) is introduced to measure tc, satisfying tc > 2τf for retention, while satisfying tc < τf/3 for passing. Inspection of the relationship between film deformation and falling height indicates that Vbub enlarges with increasing Ds and C* but shrinks with increasing G and release height Hs0.
{"title":"Dynamics of sphere impact on a suspended film with glycerol and surfactant","authors":"Dan Li, Xuemin Ye, Xiangjie You, Chunxi Li","doi":"10.1063/5.0208976","DOIUrl":"https://doi.org/10.1063/5.0208976","url":null,"abstract":"Understanding the dynamics and inherent mechanisms of sphere impact on suspended films is important for improving sphere-film separation techniques. In this study, we conducted experiments to investigate the dynamics of sphere impact on suspended films and examine typical phenomena. We revealed the effects of dynamic viscosity and surface tension of films by altering the glycerol content (G) and the relative surfactant concentration (C*) and elucidated the characteristics of film deformation, sphere trajectory (hs), and contact time (tc). Moreover, we obtained the influences of sphere and film properties on bubble volume (Vbub) by analyzing force balance. The results indicate that three modes are observed and divided using the dimensionless energy parameter E* = Ek0/(ΔEfs + Evis) based on energy analysis, considering the sphere kinetic energy (Ek0), film surface energy increment (ΔEfs), and viscous dissipation (Evis): satisfying E* < 1, retention occurs; satisfying 1 < E* < 127.7(Ds/Df)2 (where Ds is the sphere diameter, Df is the film diameter), bubble entrainment passing appears; satisfying E* > 127.7(Ds/Df)2, non-bubble entrainment passing emerges. During retention, increasing G and C* causes film surface elasticity and hs to present a trend of first rising and then falling. For passing, the increase in G reduces deformability, leading hs to decrease, while increasing C* makes the film more susceptible to deformation, causing hs to increase. In addition, a film vibration period (τf) is introduced to measure tc, satisfying tc > 2τf for retention, while satisfying tc < τf/3 for passing. Inspection of the relationship between film deformation and falling height indicates that Vbub enlarges with increasing Ds and C* but shrinks with increasing G and release height Hs0.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141704165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The drag force and flow-induced noise of underwater vehicles significantly affect their hydrodynamic and stealth performance. This paper investigates the impact of helical grooves on the drag force and flow-induced noise of underwater vehicles through numerical simulations of the flow around cylinders with two types of helical grooves under various subcritical Reynolds numbers. The simulation scheme employs the large-eddy simulation framework combined with the Lighthill acoustic analogy method. The results show that the helical-groove structure can achieve reductions of up to 30% in drag and 5 dB in noise. These helical grooves have a significant effect in terms of suppressing the formation of a Karman vortex street downstream of the cylinder. Under subcritical Reynolds numbers, the drag-reduction effect of the helically grooved cylinder decreases as the number of helical grooves increases, while the noise-reduction effect increases with increasing number of helical grooves.
{"title":"Impact of helical grooves on drag force and flow-induced noise of a cylinder under subcritical Reynolds numbers","authors":"Mingyang Xu, Wulong Hu, Zhangze Jiang","doi":"10.1063/5.0216273","DOIUrl":"https://doi.org/10.1063/5.0216273","url":null,"abstract":"The drag force and flow-induced noise of underwater vehicles significantly affect their hydrodynamic and stealth performance. This paper investigates the impact of helical grooves on the drag force and flow-induced noise of underwater vehicles through numerical simulations of the flow around cylinders with two types of helical grooves under various subcritical Reynolds numbers. The simulation scheme employs the large-eddy simulation framework combined with the Lighthill acoustic analogy method. The results show that the helical-groove structure can achieve reductions of up to 30% in drag and 5 dB in noise. These helical grooves have a significant effect in terms of suppressing the formation of a Karman vortex street downstream of the cylinder. Under subcritical Reynolds numbers, the drag-reduction effect of the helically grooved cylinder decreases as the number of helical grooves increases, while the noise-reduction effect increases with increasing number of helical grooves.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141715245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work investigates the vortex suppression performance and mechanism of ribs on high-quality ratio cylinders. Through wind tunnel tests and numerical simulations, the surface wind pressure distribution characteristics and flow separation phenomena of different ribbed cylinders are explored, and the spanwise correlation and nonlinear vibration characteristics of vortex-induced vibrations of ribbed cylinder models are analyzed. The main conclusions are as follows: ribs change the position of the boundary layer separation point, and the difference in size of left and right separated vortices causes a pressure jump phenomenon, altering the wind pressure distribution of the segment model and reducing the wind pressure, resulting in an increase in the locked wind speed of the ribbed cylinder. Complex separated vortices form behind the ribs, affecting the size of the wake vortex and reducing the stability of the segment model at locked wind speeds. Cylinders with four ribs exhibit good vortex-induced vibration suppression performance at 0° and 45° positioning angles. In addition, the cylinder with four installed ribs cylinders exhibits two locked wind speed regions, each showing different motion states: at the primary locked wind speed, they mainly demonstrate quasi-periodic vibrations and degraded quasi-periodic vibrations, while at the secondary locked wind speed, primarily in a chaotic state dominated by high-frequency harmonic components. These research findings have significant implications for future studies and practical engineering applications.
{"title":"Study on the vortex-induced vibration and flow control of ribbed circular cylinder","authors":"Dongmei Huang, Shuguang Yang, Yue Wang, Lufeng Yang, Shuang Wu, Haobo Liang","doi":"10.1063/5.0213698","DOIUrl":"https://doi.org/10.1063/5.0213698","url":null,"abstract":"This work investigates the vortex suppression performance and mechanism of ribs on high-quality ratio cylinders. Through wind tunnel tests and numerical simulations, the surface wind pressure distribution characteristics and flow separation phenomena of different ribbed cylinders are explored, and the spanwise correlation and nonlinear vibration characteristics of vortex-induced vibrations of ribbed cylinder models are analyzed. The main conclusions are as follows: ribs change the position of the boundary layer separation point, and the difference in size of left and right separated vortices causes a pressure jump phenomenon, altering the wind pressure distribution of the segment model and reducing the wind pressure, resulting in an increase in the locked wind speed of the ribbed cylinder. Complex separated vortices form behind the ribs, affecting the size of the wake vortex and reducing the stability of the segment model at locked wind speeds. Cylinders with four ribs exhibit good vortex-induced vibration suppression performance at 0° and 45° positioning angles. In addition, the cylinder with four installed ribs cylinders exhibits two locked wind speed regions, each showing different motion states: at the primary locked wind speed, they mainly demonstrate quasi-periodic vibrations and degraded quasi-periodic vibrations, while at the secondary locked wind speed, primarily in a chaotic state dominated by high-frequency harmonic components. These research findings have significant implications for future studies and practical engineering applications.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141706199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Da Gao, Guobiao Cai, Huanying Zhang, Baiyi Zhang, Lihui Liu, Bijiao He
As the lander approaches the lunar surface, the engine plumes impinge on the lunar regolith and entrain lunar dust from the surface. This plume–surface interaction and the resulting dispersion of lunar dust form a multi-physics, multi-scale problem, which becomes even more complex under multi-engine conditions. This study employed the direct simulation Monte Carlo method to simulate the plume–surface interaction flow field of a four-engine lunar lander at various landing altitudes and lunar surface angles. Flow characteristics were analyzed, and the impact of the plume and backflow on the lander was assessed. Subsequently, lunar dust simulation was conducted using the plume field as a basis. The study determined the spatial distribution of particles with different diameters at various landing altitudes and surface angles, as well as their impact velocities on the lander. Furthermore, taking into account the variations in the lander's altitude and attitude, a dynamic simulation of lunar dust during the landing process was conducted. This process resulted in the dynamic distribution of lunar dust during landing, laying the groundwork for real-time simulation of lunar dust distribution and reliable visualization during landing simulations. These findings are valuable for assessing and mitigating the hazards posed by lunar dust.
{"title":"Numerical simulation of plume–surface interaction and lunar dust dispersion during lunar landing using four engines","authors":"Da Gao, Guobiao Cai, Huanying Zhang, Baiyi Zhang, Lihui Liu, Bijiao He","doi":"10.1063/5.0213648","DOIUrl":"https://doi.org/10.1063/5.0213648","url":null,"abstract":"As the lander approaches the lunar surface, the engine plumes impinge on the lunar regolith and entrain lunar dust from the surface. This plume–surface interaction and the resulting dispersion of lunar dust form a multi-physics, multi-scale problem, which becomes even more complex under multi-engine conditions. This study employed the direct simulation Monte Carlo method to simulate the plume–surface interaction flow field of a four-engine lunar lander at various landing altitudes and lunar surface angles. Flow characteristics were analyzed, and the impact of the plume and backflow on the lander was assessed. Subsequently, lunar dust simulation was conducted using the plume field as a basis. The study determined the spatial distribution of particles with different diameters at various landing altitudes and surface angles, as well as their impact velocities on the lander. Furthermore, taking into account the variations in the lander's altitude and attitude, a dynamic simulation of lunar dust during the landing process was conducted. This process resulted in the dynamic distribution of lunar dust during landing, laying the groundwork for real-time simulation of lunar dust distribution and reliable visualization during landing simulations. These findings are valuable for assessing and mitigating the hazards posed by lunar dust.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141705231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The unsteady flow surrounding two fixed diamond cylinders is analyzed at Reynolds number 100 over normalized center-to-center spacing ratios 2−15. By analyzing the contours of instantaneous vorticity, variations of recirculation length, surface pressure, and fluid forcing of cylinders, the value of normalized critical spacing is found to be 3.4. In the reattachment zone below critical spacing, vortex-shedding from the upstream (UC) and downstream (DC) cylinders is anti-phase. At the critical spacing, regular vortex-shedding commences also from the UC, and vortex-shedding from the cylinders becomes phase synchronized for the first time. The analysis of a vortex-shedding cycle at the critical spacing reveals that the cylinders shed vortices at the same frequency, but with a time delay. Impingement of vortices shed from the UC on the DC strengthens vorticity around the DC and shifts the instantaneous position of its forward stagnation point from the leading edge. The understanding that locations of stagnation points govern the direction and magnitude of lift force comes from the analysis of flow at the critical gap. When the surface bounded by stagnation points is occupied mostly with negative vorticity, the instantaneous lift is negative and vice versa. At critical spacing, mean streamlines show the emergence of an anti-wake at forward stagnation point of the DC for the first time. Over the entire range of cylinder separation, nine distinct patterns of separation topologies are identified. Below critical spacing, both pressure and viscous drag components, and hence, total drag of the DC are negative or upstream-acting.
{"title":"Flow past two diamond-section cylinders in tandem arrangement at a low Reynolds number","authors":"Shravan Kumar Mishra, Subhankar Sen","doi":"10.1063/5.0210896","DOIUrl":"https://doi.org/10.1063/5.0210896","url":null,"abstract":"The unsteady flow surrounding two fixed diamond cylinders is analyzed at Reynolds number 100 over normalized center-to-center spacing ratios 2−15. By analyzing the contours of instantaneous vorticity, variations of recirculation length, surface pressure, and fluid forcing of cylinders, the value of normalized critical spacing is found to be 3.4. In the reattachment zone below critical spacing, vortex-shedding from the upstream (UC) and downstream (DC) cylinders is anti-phase. At the critical spacing, regular vortex-shedding commences also from the UC, and vortex-shedding from the cylinders becomes phase synchronized for the first time. The analysis of a vortex-shedding cycle at the critical spacing reveals that the cylinders shed vortices at the same frequency, but with a time delay. Impingement of vortices shed from the UC on the DC strengthens vorticity around the DC and shifts the instantaneous position of its forward stagnation point from the leading edge. The understanding that locations of stagnation points govern the direction and magnitude of lift force comes from the analysis of flow at the critical gap. When the surface bounded by stagnation points is occupied mostly with negative vorticity, the instantaneous lift is negative and vice versa. At critical spacing, mean streamlines show the emergence of an anti-wake at forward stagnation point of the DC for the first time. Over the entire range of cylinder separation, nine distinct patterns of separation topologies are identified. Below critical spacing, both pressure and viscous drag components, and hence, total drag of the DC are negative or upstream-acting.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141697036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, circular and drop-shaped pin-fins were employed to investigate the influence of pin-fins on the thermal behavior and flow characteristics of finned tubes using a combination of experimental and numerical methods. The configuration of in-line pin-fins was analyzed and compared with that of a smooth tube. The analysis covered Reynolds numbers spanning from Re = 7.03 × 103 to 35.17 × 103. Thermal and hydraulic contours were depicted. Two methodologies were utilized to assess the overall performance. The outcomes demonstrated that the average Nusselt number for the finned tubes equipped with drop and circular pin-fins rose by approximately 50.03%–93.1% and 59.59%–77.08%, respectively, in comparison to the smooth circular tube. Moreover, the drop-shaped pin-fins on the tube displayed a reduced friction factor, leading to a reduction of 1.36%–7.95% in comparison to the circular counterpart. Furthermore, both drop and circular pin-fins on the tubes exhibited approximately 2.93%–54.89% and 7.33%–37.1% higher efficiency, respectively, compared to the smooth tube. Generalized correlations were developed to compute the Nusselt number, friction factor, and effectiveness in relation to the Reynolds number, with the aim of providing guidance for future research and design efforts in heat exchangers incorporating pin-fin tubes. The utilization of tubes featuring drop-shaped pin-fins plays a significant role in energy conservation.
{"title":"The impact of drop-shaped pin-fins on the thermal and hydraulic characteristics of a finned tube","authors":"Rawad Deeb","doi":"10.1063/5.0218237","DOIUrl":"https://doi.org/10.1063/5.0218237","url":null,"abstract":"In this study, circular and drop-shaped pin-fins were employed to investigate the influence of pin-fins on the thermal behavior and flow characteristics of finned tubes using a combination of experimental and numerical methods. The configuration of in-line pin-fins was analyzed and compared with that of a smooth tube. The analysis covered Reynolds numbers spanning from Re = 7.03 × 103 to 35.17 × 103. Thermal and hydraulic contours were depicted. Two methodologies were utilized to assess the overall performance. The outcomes demonstrated that the average Nusselt number for the finned tubes equipped with drop and circular pin-fins rose by approximately 50.03%–93.1% and 59.59%–77.08%, respectively, in comparison to the smooth circular tube. Moreover, the drop-shaped pin-fins on the tube displayed a reduced friction factor, leading to a reduction of 1.36%–7.95% in comparison to the circular counterpart. Furthermore, both drop and circular pin-fins on the tubes exhibited approximately 2.93%–54.89% and 7.33%–37.1% higher efficiency, respectively, compared to the smooth tube. Generalized correlations were developed to compute the Nusselt number, friction factor, and effectiveness in relation to the Reynolds number, with the aim of providing guidance for future research and design efforts in heat exchangers incorporating pin-fin tubes. The utilization of tubes featuring drop-shaped pin-fins plays a significant role in energy conservation.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141705313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Graikos, H. Tang, M. Carnevale, N. Y. Bailey, J. Scobie
The presence of a rotating disk adjacent to a stationary disk forms a rotor–stator cavity known as a wheel-space. It is necessary for gas turbine wheel-spaces to be purged with sealing flow bled from the compressor to counteract the harmful effects of ingress. This paper presents a combined experimental, theoretical, and computational study of rotationally induced ingress in rotor–stator systems. Measurements were made in a wheel-space with an axial clearance rim seal under axisymmetric conditions in the absence of a mainstream annulus through-flow. Ingress was quantified using a gas concentration technique and the flow structure in the cavity was explored with static and total pressure measurements to determine the swirl ratio. A low-order theoretical model was developed based on the boundary layer momentum-integral equations. The theory gave excellent results when predicting the effects of ingress and purge flows on the radial pressure and swirl gradients. Unsteady Reynolds-Averaged Navier–Stokes computations were conducted to provide greater fluid dynamic insight into the wheel-space flow structure and ingress through the rim seal. The computational results demonstrated some of the closest agreement with experimental measurements of ingress available in the literature, showing that rotationally induced ingress is dominated by unsteady large-scale structures in the rim seal gap instead of the previously ascribed disk-pumping effect. The study serves as an important validation case for investigations of ingress in rotor–stator systems in more complex environments.
{"title":"Rotationally induced ingress in rotor–stator systems","authors":"D. Graikos, H. Tang, M. Carnevale, N. Y. Bailey, J. Scobie","doi":"10.1063/5.0207140","DOIUrl":"https://doi.org/10.1063/5.0207140","url":null,"abstract":"The presence of a rotating disk adjacent to a stationary disk forms a rotor–stator cavity known as a wheel-space. It is necessary for gas turbine wheel-spaces to be purged with sealing flow bled from the compressor to counteract the harmful effects of ingress. This paper presents a combined experimental, theoretical, and computational study of rotationally induced ingress in rotor–stator systems. Measurements were made in a wheel-space with an axial clearance rim seal under axisymmetric conditions in the absence of a mainstream annulus through-flow. Ingress was quantified using a gas concentration technique and the flow structure in the cavity was explored with static and total pressure measurements to determine the swirl ratio. A low-order theoretical model was developed based on the boundary layer momentum-integral equations. The theory gave excellent results when predicting the effects of ingress and purge flows on the radial pressure and swirl gradients. Unsteady Reynolds-Averaged Navier–Stokes computations were conducted to provide greater fluid dynamic insight into the wheel-space flow structure and ingress through the rim seal. The computational results demonstrated some of the closest agreement with experimental measurements of ingress available in the literature, showing that rotationally induced ingress is dominated by unsteady large-scale structures in the rim seal gap instead of the previously ascribed disk-pumping effect. The study serves as an important validation case for investigations of ingress in rotor–stator systems in more complex environments.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141694940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jianyong Yin, Yongxue Zhang, Mingkai Ma, Lei Tian, Xianrong Du
Investigating the interaction between the near-wall cavitation bubble and the air bubble has great significance for understanding the mechanism of air entrainment to alleviate cavitation in actual hydraulic engineering. To quantify the effect of the air bubble on the multi-cycle dynamics of the near-wall cavitation bubble, a more comprehensive compressible three-phase model considering the phase-change process was developed based on OpenFOAM, and corresponding validation was performed by comparing the simulated bubble shape with the published experimental values. The key features of the multi-cyclical evolution of the cavitation bubble are nicely reproduced based on the current numerical model. For the cavitation bubble near the solid wall containing a hemispherical air bubble, the simulated results reveal that the air bubble can reflect the shock wave and thus prevent it from impacting directly on the solid wall, which will help to uncover the microscopic mechanism of aeration avoiding cavitation damage. The dynamical features of the cavitation bubble at different dimensionless distances (γ1) and dimensionless sizes (ε) are investigated and analyzed. For the near-wall cavitation bubble with an air-entrapping hole, the air hole plays a crucial role in the multi-cycle dynamics of the cavitation bubble, leading to the bubble that is always far away from both the air hole and the solid wall. Thus, the current results may provide a potential application for preventing the wall damage caused by the impact of the liquid jet.
{"title":"The multi-cycle dynamics of the cavitation bubble near the solid wall with an air-entrapping hole or a hemispherical air bubble: A numerical study","authors":"Jianyong Yin, Yongxue Zhang, Mingkai Ma, Lei Tian, Xianrong Du","doi":"10.1063/5.0218902","DOIUrl":"https://doi.org/10.1063/5.0218902","url":null,"abstract":"Investigating the interaction between the near-wall cavitation bubble and the air bubble has great significance for understanding the mechanism of air entrainment to alleviate cavitation in actual hydraulic engineering. To quantify the effect of the air bubble on the multi-cycle dynamics of the near-wall cavitation bubble, a more comprehensive compressible three-phase model considering the phase-change process was developed based on OpenFOAM, and corresponding validation was performed by comparing the simulated bubble shape with the published experimental values. The key features of the multi-cyclical evolution of the cavitation bubble are nicely reproduced based on the current numerical model. For the cavitation bubble near the solid wall containing a hemispherical air bubble, the simulated results reveal that the air bubble can reflect the shock wave and thus prevent it from impacting directly on the solid wall, which will help to uncover the microscopic mechanism of aeration avoiding cavitation damage. The dynamical features of the cavitation bubble at different dimensionless distances (γ1) and dimensionless sizes (ε) are investigated and analyzed. For the near-wall cavitation bubble with an air-entrapping hole, the air hole plays a crucial role in the multi-cycle dynamics of the cavitation bubble, leading to the bubble that is always far away from both the air hole and the solid wall. Thus, the current results may provide a potential application for preventing the wall damage caused by the impact of the liquid jet.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141717146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Turbulence in plasmas and fluids","authors":"Chunxiao Xu, P. Terry","doi":"10.1063/5.0223481","DOIUrl":"https://doi.org/10.1063/5.0223481","url":null,"abstract":"","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141696095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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