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Keywords: viscous fluid, stratification, flow around a square cylinder, direct numerical simulation, visualization, flow regime.

Summary

The two-dimensional density stratified (in the vertical direction) viscous fluid flows around a horizontal square cylinder (moving in the horizontal direction) have been simulated on supercomputers using the numerical method SMIF (splitting on physical factors method for incompressible flows) with a hybrid explicit finite difference scheme (with second-order accuracy in space and monotonous) on the basis of the Navier-Stokes equations in the Boussinesq approximation. The original refined classification of the two-dimensional flow regimes has been obtained at Reynolds numbers less than 200 and internal Froude numbers between 0.1 and 100 using an optimal computational grid of 800 x 500. This classification with original simple names for the six flow regimes is based on the stream line patterns corresponding to the steady state flow which was formed after a pulse start of the cylinder. The formation process of two symmetric hanging vortices in the near wake connected with two hanging sheets of density (detected at shadowgraphs) has been investigated for Froude and Reynolds numbers of 0.1 and 50 respectively. The patterns of isolines of the horizontal density gradient of these flows are in a good agreement with the correspondent schlieren images (shadowgraphs) of the experiments. But the simulations in this paper show velocity vectors patterns that prove that the conclusions of the experiments concerning the discontinuity of the velocity field in the vicinity of these hanging sheets of density (only at the base of the different schlieren images) are completely wrong.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 105 PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON ENGINEERING COMPUTATIONAL TECHNOLOGY Edited by: Paper 70 Classification of Regimes of the Stratified Fluid Flows around a Square Cylinder P.V. Matyushin and V.A. Gushchin Institute for Computer Aided Design, Russian Academy of Sciences, Moscow, Russia doi:10.4203/ccp.105.70 purchase the full-text of this paper Full Bibliographic Reference for this paper P.V. Matyushin, V.A. Gushchin, "Classification of Regimes of the Stratified Fluid Flows around a Square Cylinder", in , (Editors), "Proceedings of the Ninth International Conference on Engineering Computational Technology", Civil-Comp Press, Stirlingshire, UK, Paper 70, 2014. doi:10.4203/ccp.105.70 Keywords: viscous fluid, stratification, flow around a square cylinder, direct numerical simulation, visualization, flow regime. Summary The two-dimensional density stratified (in the vertical direction) viscous fluid flows around a horizontal square cylinder (moving in the horizontal direction) have been simulated on supercomputers using the numerical method SMIF (splitting on physical factors method for incompressible flows) with a hybrid explicit finite difference scheme (with second-order accuracy in space and monotonous) on the basis of the Navier-Stokes equations in the Boussinesq approximation. The original refined classification of the two-dimensional flow regimes has been obtained at Reynolds numbers less than 200 and internal Froude numbers between 0.1 and 100 using an optimal computational grid of 800 x 500. This classification with original simple names for the six flow regimes is based on the stream line patterns corresponding to the steady state flow which was formed after a pulse start of the cylinder. The formation process of two symmetric hanging vortices in the near wake connected with two hanging sheets of density (detected at shadowgraphs) has been investigated for Froude and Reynolds numbers of 0.1 and 50 respectively. The patterns of isolines of the horizontal density gradient of these flows are in a good agreement with the correspondent schlieren images (shadowgraphs) of the experiments. But the simulations in this paper show velocity vectors patterns that prove that the conclusions of the experiments concerning the discontinuity of the velocity field in the vicinity of these hanging sheets of density (only at the base of the different schlieren images) are completely wrong. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £45 +P&P)
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