NUMERICAL MODELING OF BACKWARD-FACING STEP FLOW VIA COMPUTATIONAL FLUID DYNAMICS

As a fundamental case for problems of fluid mechanics, examination of flow separation and its reattachment is important for engineering applications. Considering the significance of the subject, backward-facing step flow has been modeled via Computational Fluid Dynamics (CFD) based on an experimental study previously done at Re = 5000. Steady simulations have been conducted by k-ε Renormalization Group (RNG) considering the same flow conditions of the reference study. Pressure distributions, streamwise and cross-stream velocity components, velocity magnitude values with streamline patterns and turbulence kinetic energy values have been presented by using contour graphics. Furthermore, the stations for pressure distributions, velocity profiles for streamwise components and turbulence kinetic energy values have been defined for evolution of related data. Lower pressure zone for the wake region of the backward-facing step has been attained due to flow separation. Separation of the upstream boundary layer has been seen and it became a curved one. Moreover, turbulence level of the step wake has been obtained as higher than those of any other points. Transition to core flow has been attained at y* = 1.1 that is above the step height. Flow oscillations have been observed for x* ≥ 2 and y* ≤ 1 since the fluctuations for these values were effective in the wake region. To sum up, the dimensionless reattachment length has been numerically obtained as 5.92 which is very good agreement with the experimental results at same Reynolds number. The deviation from the reference results is from 0.34 % to 1.33 %.

Keywords:

Backward-facing step, Flow separation, k-ε RNG Reattachment length, Turbulence,

PDF

___

[1] Chen, L., Asai, K., Nonomura, T., Xi, G. and Liu, T., (2018). A review of backward-facing step (BFS) flow mechanisms, heat transfer and control, Thermal Science and Engineering Progress, 6, 194-216.
[2] Teso-Fz-Betoño, D., Juica, M., Portal-Porras, K., Fernandez-Gamiz, U. and Zulueta, E., (2021). Estimating the reattachment length by realizing a comparison between URANS k-omega SST and LES WALE models on a symmetric geometry, Symmetry, 13(9), 1555.
[3] Arthur, J.K., (2023). A narrow-channeled backward-facing step flow with or without a pin–fin insert: Flow in the separated region, Experimental Thermal and Fluid Science, 141, 110791.
[4] Detto, M., Katul, G.G., Siqueira, M., Juang, J.Y. and Stoy, P., (2008). The structure of turbulence near a tall forest edge: The backward‐facing step flow analogy revisited, Ecological Applications, 18(6), 1420-1435.
[5] Deepa, G. and Murali, G., (2014). Effects of viscous dissipation on unsteady MHD free convective flow with thermophoresis past a radiate inclined permeable plate, Iranian Journal of Science and Technology, 38(3.1), 379-388.
[6] Jiaqiang, E., Cai, L., Li, J., Ding, J., Chen, J. and Luo, B., (2022). Effects analysis on the catalytic combustion and heat transfer performance enhancement of a non-premixed hydrogen/air micro combustor, Fuel, 309, 122125.
[7] Zuo, W., Zhao, H., Jiaqiang, E., Li, Q. and Li, D., (2022). Numerical investigations on thermal performance and flame stability of hydrogen-fueled micro tube combustor with injector for thermophotovoltaic applications, International Journal of Hydrogen Energy, 47(39), 17454-17467.
[8] Giannopoulos, A. and Aider, J.L., (2020). Prediction of the dynamics of a backward-facing step flow using focused time-delay neural networks and particle image velocimetry data-sets, International Journal of Heat and Fluid Flow, 82, 108533.
[9] Oder, J., Shams, A., Cizelj, L. and Tiselj, I., (2019). Direct numerical simulation of low-Prandtl fluid flow over a confined backward facing step, International Journal of Heat and Mass Transfer, 142, 118436.
[10] Jovic, S. and Driver, D., (1995). Reynolds number effect on the skin friction in separated flows behind a backward-facing step, Experiments in Fluids, 18, 464-467.
[11] Kasagi, N. and Matsunaga, A., (1995). Three-dimensional particle-tracking velocimetry measurement of turbulence statistics and energy budget in a backward-facing step flow, International Journal of Heat and Fluid Flow, 16(6), 477-485.
[12] Scarano, F., Benocci, C. and Riethmuller, M.L., (1999). Pattern recognition analysis of the turbulent flow past a backward facing step, Physics of Fluids, 11(12), 3808-3818.
[13] Wengle, H., Huppertz, A., Bärwolff, G. and Janke, G., (2001). The manipulated transitional backward-facing step flow: an experimental and direct numerical simulation investigation, European Journal of Mechanics-B/Fluids, 20(1), 25-46.
[14] Kostas, J., Soria, J. and Chong, M., (2002). Particle image velocimetry measurements of a backward-facing step flow, Experiments in Fluids, 33, 838-853.
[15] Furuichi, N., Hachiga, T. and Kumada, M., (2004). An experimental investigation of a large-scale structure of a two-dimensional backward-facing step by using advanced multi-point LDV, Experiments in Fluids, 36, 274-281.
[16] Nie, J.H. and Armaly, B.F., (2004). Reverse flow regions in three-dimensional backward-facing step flow, International Journal of Heat and Mass Transfer, 47(22), 4713-4720.
[17] Schram, C., Rambaud, P. and Riethmuller, M.L., (2004). Wavelet based eddy structure eduction from a backward facing step flow investigated using particle image velocimetry, Experiments in Fluids, 36, 233-245.
[18] Bouda, N.N., Schiestel, R., Amielh, M., Rey, C. and Benabid, T., (2008). Experimental approach and numerical prediction of a turbulent wall jet over a backward facing step, International Journal of Heat and Fluid Flow, 29(4), 927-944.
[19] Wu, Y., Ren, H. and Tang, H., (2013). Turbulent flow over a rough backward-facing step, International Journal of Heat and Fluid Flow, 44, 155-169.
[20] Nadge, P.M. and Govardhan, R.N., (2014). High Reynolds number flow over a backward-facing step: structure of the mean separation bubble, Experiments in Fluids, 55, 1-22.
[21] Yamada, S. and Nakamura, H., (2016). Construction of 2D-3C PIV and high-speed infrared thermography combined system for simultaneous measurement of flow and thermal fluctuations over a backward facing step, International Journal of Heat and Fluid Flow, 61, 174-182.
[22] Le, H., Moin, P. and Kim, J., (1997). Direct numerical simulation of turbulent flow over a backward-facing step, Journal of Fluid Mechanics, 330, 349-374.
[23] Chiang, T.P., Sheu, T.W. and Fang, C.C., (1999). Numerical investigation of vortical evolution in a backward-facing step expansion flow, Applied Mathematical Modelling, 23(12), 915-932.
[24] Avancha, R.V. and Pletcher, R.H., (2002). Large eddy simulation of the turbulent flow past a backward-facing step with heat transfer and property variations, International Journal of Heat and Fluid Flow, 23(5), 601-614.
[25] Dejoan, A. and Leschziner, M.A., (2004). Large eddy simulation of periodically perturbed separated flow over a backward-facing step, International Journal of Heat and Fluid Flow, 25(4), 581-592.
[26] Aider, J.L. and Danet, A., (2006). Large-eddy simulation study of upstream boundary conditions influence upon a backward-facing step flow, Comptes Rendus Mécanique, 334(7), 447-453.
[27] Barri, M., El Khoury, G.K., Andersson, H.I. and Pettersen, B., (2010). DNS of backward‐facing step flow with fully turbulent inflow, International Journal for Numerical Methods in Fluids, 64(7), 777-792.
[28] El Khoury, G.K., Andersson, H.I., Barri, M. and Pettersen, B., (2010). Massive separation of turbulent Couette flow in a one-sided expansion channel, International Journal of Heat and Fluid Flow, 31(3), 274-283.
[29] Jürgens, W. and Kaltenbach, H.J., (2012). The effect of sweep on the forced transitional flow over a backward-facing step, Computers and Fluids, 59, 1-10.
[30] Kanchi, H., Sengupta, K. and Mashayek, F., (2013). Effect of turbulent inflow boundary condition in LES of flow over a backward-facing step using spectral element method, International Journal of Heat and Mass Transfer, 62, 782-793.
[31] Togun, H., Safaei, M.R., Sadri, R., Kazi, S.N., Badarudin, A., Hooman, K. and Sadeghinezhad, E., (2014). Numerical simulation of laminar to turbulent nanofluid flow and heat transfer over a backward-facing step, Applied Mathematics and Computation, 239, 153-170.
[32] Amiri, A., Arzani, H.K., Kazi, S.N., Chew, B.T. and Badarudin, A., (2016). Backward-facing step heat transfer of the turbulent regime for functionalized graphene nanoplatelets based water–ethylene glycol nanofluids, International Journal of Heat and Mass Transfer, 97, 538-546.
[33] Xu, J.H., Zou, S., Inaoka, K. and Xi, G.N., (2017). Effect of Reynolds number on flow and heat transfer in incompressible forced convection over a 3D backward-facing step, International Journal of Refrigeration, 79, 164-175.
[34] Yagmur, S., Dogan, S., Aksoy, M.H. and Goktepeli, I., (2020). Turbulence modeling approaches on unsteady flow structures around a semi-circular cylinder, Ocean Engineering, 200, 107051.
[35] Goktepeli, I. and Atmaca, U., (2023). Examination of air flow characteristics over an open rectangular cavity between the plates, International Journal of Aeroacoustics, 22(3-4), 351-370.
[36] Murali, G., Paul, A.J.I.T. and Narendrababu, N.V., (2015). Numerical study of chemical reaction effects on unsteady MHD fluid flow past an infinite vertical plate embedded in a porous medium with variable suction, Electronic Journal of Mathematical Analysis and Applications, 3(2), 179-192.
[37] Murali, G. and Narendrababu, N.V., (2021). Convective MHD jeffrey fluid flow due to vertical plates with pulsed fluid suction: A numerical study, Journal of Computational Applied Mechanics, 54(1), 36-48.
[38] Kang, S. and Choi, H., (2002). Suboptimal feedback control of turbulent flow over a backward-facing step, Journal of Fluid Mechanics, 463, 201-227.
[39] Goktepeli, I., Atmaca, U. and Cakan, A., (2020). Investigation of heat transfer augmentation between the ribbed plates via Taguchi approach and computational fluid dynamics, Journal of Thermal Science, 29, 647-666.
[40] Goktepeli, I., Atmaca, U. and Yagmur, S., (2021). Visualization of flow characteristics between the ribbed plates via Particle Image Velocimetry, Thermal Science, 25(1), 171-179.
[41] Goktepeli, I. and Atmaca, U., (2020). Numerical examination of heat transfer augmentation between the plates with square cross-sectional ribs for the staggered arrangement, Kocaeli Journal of Science and Engineering, 3(2), 33-40.
[42] Goktepeli, I. and Atmaca, U., (2021). Computational study on the effect of the staggered ribs on heat transfer phenomena between the horizontal plates, Hittite Journal of Science and Engineering, 8(1), 7-17.