Samrat Hansda , Anirban Chattopadhyay , Krishno D. Goswami , Swapan K. Pandit , Hakan F. Öztop , Mikhail A. Sheremet
{"title":"Optimizing entropy production in bi-diffusive convection within trapezoidal Porous enclosure using radiative trihybrid nanofluids and T-shaped baffle","authors":"Samrat Hansda , Anirban Chattopadhyay , Krishno D. Goswami , Swapan K. Pandit , Hakan F. Öztop , Mikhail A. Sheremet","doi":"10.1016/j.euromechflu.2025.204268","DOIUrl":"10.1016/j.euromechflu.2025.204268","url":null,"abstract":"<div><div>This study explores entropy production optimization and thermosolutal transfer enhancement in trapezoidal porous enclosure, commonly used in solar energy systems, electronic cooling, and chemical reactors. The objective is to evaluate the effects of radiative trihybrid nanoliquids on heat and mass transfer in a trapezoidal porous cavity filled with aluminum oxide, copper oxide, and silver nanoparticles dispersed in water, featuring a centrally located T-shaped cold baffle. The lower boundary of the cavity is uniformly heated and soluted, the side boundaries are cooled with low solute concentrations, and the upper boundary is insulated. The governing equations are solved using a Higher Order Compact (HOC) numerical scheme, focusing on parameters such as the Rayleigh number, radiation parameter, buoyancy ratio, and nanoparticle concentration. Results indicate that increasing the Rayleigh number from <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></math></span> to <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>6</mn></mrow></msup></mrow></math></span> significantly enhances heat and mass transfer rates. Average Nusselt and Sherwood numbers are increased up to 53.04% and 252.49%, respectively, across different configurations. Additionally, raising the radiation parameter values from 1 to 5 boosts the average Nusselt number up to 197.09%, highlighting the dominance of radiative thermal transport. The T-shaped baffle significantly influences flow patterns, reduces entropy generation, and optimizes thermal and solutal transport.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"113 ","pages":"Article 204268"},"PeriodicalIF":2.5,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143950489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Transient slow motions of a composite spherical particle","authors":"Wei C. Lai, Chia L. Chang, Huan J. Keh","doi":"10.1016/j.euromechflu.2025.204276","DOIUrl":"10.1016/j.euromechflu.2025.204276","url":null,"abstract":"<div><div>The transient translation and rotation of a composite spherical particle, consisting of an impermeable hard sphere core and a permeable porous surface layer, in a viscous fluid at low Reynolds number induced by suddenly applied continuous force and torque are analytically studied. By solving the unsteady Stokes and Brinkman equations that respectively govern the fluid flows outside and inside the porous surface layer through the Laplace transform, closed-form formulas of the starting linear and angular velocities of the composite sphere as functions of the relevant parameters are obtained. These velocities increase over time from initial values of zero to their final values, while the linear and angular accelerations of the composite sphere decrease over time, eventually approaching zero. At any elapsed time, these velocities and accelerations increase monotonically and significantly with increasing relative spatial volume and fluid permeability of the porous surface layer of the composite sphere. The transient linear and angular velocities of the composite sphere are generally increasing functions of the porosity of the surface layer, but may decrease slightly with increasing porosity when the particle-to-fluid density ratio is small. The linear and angular accelerations increase with the increase of surface layer porosity in the early stage, no longer change monotonically with its increase in the middle stage, and decrease with its increase in the later stage. The transient linear and angular velocities of the composite sphere decrease with the increase of its relative density, but the linear and angular accelerations only decrease with the increase of the relative density in the early stage and increase with the increase of the relative density in the later stage.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"113 ","pages":"Article 204276"},"PeriodicalIF":2.5,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Damping of ocean waves by a porous disk submerged in a two-layer fluid","authors":"Sunanda Saha , Swaroop Nandan Bora , Santu Das","doi":"10.1016/j.euromechflu.2025.204263","DOIUrl":"10.1016/j.euromechflu.2025.204263","url":null,"abstract":"<div><div>The wave interaction with a horizontal porous disk of negligible thickness submerged in either layer of a two-layer fluid is investigated. The solution of the wave scattering problem of the submerged disk is sought analytically by developing an eigenfunction matching approach and using linear potential flow theory. We derive a complex dispersion relation for both scenarios of the disk being placed in either layer, which is required to be solved to get the eigenvalues corresponding to the vertical eigenfunctions. The transition of the eigenvalues is analyzed for the first five solutions, shedding light on the underlying physical process of mode swapping that governs the dissipation mechanism due to porosity. The same algorithm is used to locate the required number of eigenvalues for computation. The effect of different parameters on different physical quantities is analyzed for both scenarios. Known results for a horizontal porous disk submerged in a finite-depth homogeneous fluid are recovered from the present analysis. A critical observation is the reduction in the maximum force amplitude (from 55% to 77%) with increasing values of the porosity parameter (from 2 to 20), demonstrating its enhancement influenced by porosity. In addition, we notice that the positioning of the disk near the free surface or the interface increases the wave force acting on the disk. Hence, the analysis makes it clear that the configuration of the disk plays a key role in maximizing the performance of the disk as a wave absorber.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"113 ","pages":"Article 204263"},"PeriodicalIF":2.5,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mixed convection three-dimensional Hiemenz stagnation point flow","authors":"Abdul Aziz , Tapas Ray Mahapatra , Sumanta Sidui","doi":"10.1016/j.euromechflu.2025.204267","DOIUrl":"10.1016/j.euromechflu.2025.204267","url":null,"abstract":"<div><div>This study delves into the intricate analysis of the steady mixed convection three-dimensional Hiemenz stagnation-point flows over a vertical flat wall immersed in viscous and incompressible fluid. The analysis considers the derivation of a similarity solution, incorporating <span><math><mi>γ</mi></math></span>, indicative of the shear to strain rate ratio, and <span><math><mi>λ</mi></math></span> representing a mixed convection parameter. Numerical solutions are derived meticulously for typical values of <span><math><mi>δ</mi></math></span> (which is function of <span><math><mi>γ</mi></math></span>) and <span><math><mi>λ</mi></math></span> with particular towards discerning critical values <span><math><msub><mrow><mi>λ</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> especially concerning opposing flow. Asymptotic results are obtained for large values of <span><math><mi>λ</mi></math></span> and <span><math><mi>δ</mi></math></span>. It is observed that dual solutions are present for opposing flows. It is noticed that the critical values <span><math><msub><mrow><mi>λ</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> of <span><math><mi>λ</mi></math></span> are found in opposing flow, which produce two solution branches by making saddle node bifurcation at <span><math><msub><mrow><mi>λ</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>. A stability analysis of the steady flow solutions was carried out for different values of mixed convection parameter <span><math><mi>λ</mi></math></span> and it reveals that, the lower solution branches are unstable while the upper solution branches are stable.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"113 ","pages":"Article 204267"},"PeriodicalIF":2.5,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143950488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Numerical investigation of flow over a finite wall-mounted circular cylinder at low Reynolds numbers for various aspect ratios","authors":"A. Sohankar, K. Pasha","doi":"10.1016/j.euromechflu.2025.204266","DOIUrl":"10.1016/j.euromechflu.2025.204266","url":null,"abstract":"<div><div>Three-dimensional simulations of flow over and heat transfer from a finite wall-mounted circular cylinder have been conducted for different Reynolds numbers (<em>Re</em> = 1 – 100) and aspect ratios (AR=1–8) at <em>Pr</em>= 0.7, where flow remains steady for most of <em>Re</em> and <em>AR</em> considered. It was found that the computational domain size strongly affects the results, especially at low <em>AR</em> and <em>Re</em>. Thus, for very low Re <em>,</em> where the viscous effects are more dominant, it needs to be employed a more extensive domain size. In contrast, the sensitivity to the domain size decreases with increasing <em>Re</em> and <em>AR</em>. It was also deduced that the drag coefficients decrease by increasing <em>Re</em> for all aspect ratios examined. Furthermore, with the increase of <em>AR</em> but with the same Re <em>,</em> the drag coefficients increase. Some unsteady simulations were also carried out for higher <em>Re</em> in the range of <em>Re</em>= 100–200 for <em>AR</em>= 3–8 to find the critical Reynolds numbers of the onset of vortex shedding (<em>Re</em><sub><em>cr</em></sub>). It is found that the <em>Re</em><sub><em>cr</em></sub> decreases from 195 ± 5–65 ± 5 by increasing <em>AR</em> from 3 to 8, or flow becomes unsteady in lower <em>Re</em> for higher <em>AR</em>. Furthermore<strong>,</strong> the flow structure has been examined for various <em>Re</em> and <em>AR</em>. Different types of vortices, including tip (TV), base (BV), and horseshoe (HV) vortices, as well as Kármán vortex shedding (VS), are observed for a specific range of <em>Re</em> and <em>AR</em>. It is found that contrary to cases with high <em>Re</em>, the aforementioned vortices do not form for all <em>Re</em> (1−100) and <em>AR</em> (1−8) examined.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"113 ","pages":"Article 204266"},"PeriodicalIF":2.5,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143950487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Modal analysis for incompressible fluid flow: Proposed treatment of inlet and outlet boundary conditions","authors":"Satoshi Ishikawa, Shinya Kijimoto","doi":"10.1016/j.euromechflu.2025.204271","DOIUrl":"10.1016/j.euromechflu.2025.204271","url":null,"abstract":"<div><div>This paper presents a numerical method for incompressible fluid flow. One challenge in analyzing incompressible fluid flow is that the continuity equation for such flow has no time evolution term. In the pressure correction approach, Poisson’s equation is solved iteratively, which takes most of the computational time. In our previous study, modal analysis was proposed for analyzing two-dimensional incompressible fluid flow, which avoids pressure variables and thus iterative calculation of Poisson’s equation. In this paper, we propose treating the inlet and outlet boundary conditions. Numerical results for a simple flow system and a step flow obtained using the proposed method are compared with those obtained using the artificial compressible method and the simplified marker and cell (SMAC) method. The results agree well, thereby validating the proposed boundary treatment, and the present modal analysis with a graphics processing unit is 20 times faster than the SMAC method.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"113 ","pages":"Article 204271"},"PeriodicalIF":2.5,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143950492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Macroscopic non-linear filtration law for porous media containing cylindrical and spherical inhomogeneities","authors":"V. Monchiet","doi":"10.1016/j.euromechflu.2025.204264","DOIUrl":"10.1016/j.euromechflu.2025.204264","url":null,"abstract":"<div><div>This paper provides the macroscopic non-linear filtration law of a two-phase porous medium with cylindrical or spherical inhomogeneities. At the local scale, the fluid flow in both phases of the composite porous material obeys the Forchheimer law. The macroscopic law is obtained in the framework of the non-linear variational homogenization method, considering unit cells with concentric cylinders or spheres subjected to homogeneous boundary conditions. In order to derive a closed-form expression of the macroscopic law, we employ the kinematic approach with trial velocity fields inspired by a linear solution. The resulting analytical model is then compared with numerical upper and lower bounds, demonstrating its high accuracy. Finally, we provide comparisons with numerical results for unit cells containing a population of polydisperse inclusions.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"113 ","pages":"Article 204264"},"PeriodicalIF":2.5,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Okba Mostefaoui , Santiago Gómez , Diego Lopez , Emmanuel Mignot , Nicolas Rivière
{"title":"Experimental study of the drag force applied by supercritical flows on emerging obstacles","authors":"Okba Mostefaoui , Santiago Gómez , Diego Lopez , Emmanuel Mignot , Nicolas Rivière","doi":"10.1016/j.euromechflu.2025.204262","DOIUrl":"10.1016/j.euromechflu.2025.204262","url":null,"abstract":"<div><div>Supercritical open channel flows are typically encountered in mountainous rivers, in tsunami break flood waves, or in steep flooded streets, where they can interact respectively with boulders, bridge piles, buildings, city blocks or urban furniture. Depending on the Froude number of the approaching flow and on the obstacle width compared to the water depth, the flow can either form a wall-jet like bow wave or a detached hydraulic jump, which are expected to modify the force applied on the obstacle. Thus, the present work aims to characterize the steady drag force applied on an emerging obstacle, and to provide a model of the corresponding drag coefficient. To that end, force measurements are performed on parallelepipedal obstacles within supercritical flows, for a wide range of Froude numbers and of obstacle width to water depth ratios. The drag coefficient increases with this ratio and decreases with the Froude number. A momentum-based hydraulic model explains these trends, basing on the specific force arriving on the obstacle. Once combined with the experimental asymptotic values for the very wide obstacles and large Froude numbers, the model results in a semi-empirical equation that provides accurate predictions of the drag coefficient. Strikingly, the same equation is efficient for the two kinds of flow, detached hydraulic jump and wall-jet like bow wave.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"113 ","pages":"Article 204262"},"PeriodicalIF":2.5,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Comparative study of Reynolds-averaged Navier–Stokes and partially-averaged Navier–Stokes models for cavitation flows around a hemispherical head-form body","authors":"Junyoung Park , Woochan Seok","doi":"10.1016/j.euromechflu.2025.204265","DOIUrl":"10.1016/j.euromechflu.2025.204265","url":null,"abstract":"<div><div>Cavitation causes the erosion of marine propellers and induces noise and vibration within the mechanical system. In this study, the results of Reynolds-averaged Navier–Stokes (RANS) and partially-averaged Navier–Stokes (PANS) models for detecting cavitation flows around a three-dimensional (3D) hemispherical head-form body were compared. These turbulence models can accurately depict the unsteady characteristics of cavitation flows. To investigate the effect of these turbulence models on flow characteristics, we analyzed the periodic shedding of the sheet and cloud cavitation. In addition to the shape of the cavity around the body, the pressure, velocity, turbulent kinetic energy, and turbulent viscosity were compared to identify the differences between the turbulent models. An open-source platform OpenFOAM was used for this analysis. The results revealed that the pressure coefficient in the PANS model was consistent with the experimental data. Furthermore, the PANS model provided an accurate depiction of the development process of sheet and cloud cavitation.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"113 ","pages":"Article 204265"},"PeriodicalIF":2.5,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143950486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiafu Wan, Hongyi Ding, Nan Wang, Wuhan Dong, Zhiyun Wang
{"title":"LBM simulation of bubble dynamics in a microchannel with multi-hole orifice plate","authors":"Jiafu Wan, Hongyi Ding, Nan Wang, Wuhan Dong, Zhiyun Wang","doi":"10.1016/j.euromechflu.2025.204260","DOIUrl":"10.1016/j.euromechflu.2025.204260","url":null,"abstract":"<div><div>This study employs a lattice Boltzmann method (LBM), incorporating the Allen-Cahn (A-C) phase-field model, to numerically simulate bubble dynamics in a microchannel with a multi-hole orifice plate. The influence of Weber number (<em>We</em>), non-dimensional bubble diameter (<em>γ</em>), and contact angle (<em>θ</em>) on bubble motion characteristics is thoroughly examined. Phenomena such as dynamic deformation, splitting, coalescence, and mass loss of the bubble during its passage through the multi-hole orifice plate are analyzed. Numerical results demonstrate that as the surface tension of the bubble decreases, corresponding to an increase in the Weber number, the bubble’s splitting process is facilitated as it passes through the multi-hole orifice plate. Additionally, two critical Weber numbers are identified in the study, delineating three different behaviors of the bubble as its passage, with these behaviors being influenced by changes in the non-dimensional bubble diameter. An increase in contact angle significantly prolongs the passage time <em>t</em> * , especially at higher <em>We</em> numbers. The most substantial increase of <em>t</em> * occurs at a Weber number of 27.24 when the contact angle shifts from 125 to 150 degrees, reaching a maximum of 64.13 %. Furthermore, the residual mass ratio of bubbles post-passage diminishes, recording its lowest at the highest Weber number and contact angle (<em>We</em> = 27.24, <em>θ</em> = 150°), standing at 0.71.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"113 ","pages":"Article 204260"},"PeriodicalIF":2.5,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}