THERMAL SCIENCE

International Scientific Journal

Thermal Science - Online First

online first only

Experimental and CFD analysis of MHD flow around smooth sphere and sphere with dimples in subcritical and critical regimes

ABSTRACT
An overview of previous researches related to the problem of flow around a bluff-body, using experimental and numerical methods, is presented in the paper. Experimental investigation was performed by a Laser Doppler Anemometer (LDA), measuring velocity components of the water flow around a smooth sphere and a sphere with dimples in square channels. Measurement results in subcritical velocity flow field, velocity fluctuation components, lift, drag and pressure coefficients, and 2D Reynolds stress at quasi-stationary flow are conducted using 1D LDA probe. The obtained experimental results are compared with numerical simulations, which are performed using the ANSYS-CFX software. For the numerical simulations of quasi-steady-state flow, k-ω turbulent model was used, while for numerical simulation of unsteady fluid flow and for the comparison of results related to the eddy structures, vortex shedding and Reynolds stresses, Detached Eddy Simulation were used. Since the obtained results of experimental and numerical investigation of flow around smooth sphere and sphere with dimples showed good agreement, the considered flow problem was expanded by introducing the influence of a transverse magnetic field with a slight modification of the electrical conductivity of the working fluid. The other physical properties of the fluid remained the same, which also corresponds to realistically possible physical conditions. Numerical simulations were performed for three different values of Hartmann number and very small values of Reynolds magnetic number (inductionless approximation). Comparisons and analyzes of the results were made for the cases containing a magnetic field and those with an absence of a magnetic field.
KEYWORDS
PAPER SUBMITTED: 2020-04-30
PAPER REVISED: 2020-05-24
PAPER ACCEPTED: 2020-05-29
PUBLISHED ONLINE: 2020-06-07
DOI REFERENCE: https://doi.org/10.2298/TSCI200430197B
REFERENCES
  1. Coutanceau, M., Bouard, R., Experimental determination of the main features of the viscous flow in the wake of a circular cylinder in uniform translation. Part 1. Steady flow, J. Fluid Mech., (1977), 79, pp. 231-256.
  2. Cliffe, K. A., Tavener, S. J., The effect of cylinder rotation and blockage ratio on the onset of periodic flows, J. Fluid Mech., (2004), 501, pp. 125-133.
  3. Behr, M., et al., Incompressible flow past a circular cylinder: dependence of the computed flow field on the location of the lateral boundaries, Comput. Meth. Appl. Mech. Eng., (1995), 123, pp. 309-316.
  4. Zovatto, L., Pedrizzetti, G., Flow about a circular cylinder between parallel walls, J. Fluid Mech., (2001), 440, pp. 1-25.
  5. Anagnostopoulos, P., et al., Numerical study of the blockage effects on viscous flow past a circular cylinder, Int. J. Numer. Meth. Fluids, (1996), 22, pp. 1061-1074.
  6. Sahin, M., Owens, R.G., A numerical investigation of wall effects up to high blockage ratios on two-dimensional flow past a confined circular cylinder, Phys. Fluids, (2004), 16, pp. 1305-1320.
  7. Bakic, V., et al., Experimental investigation of turbulent structures of flow around a sphere, Thermal Science, (2006), 10 (2), pp. 97-112.
  8. Haverkort, J. W., Peeters, T. W. JMagnetohydrodynamics of insulating spheres, Magnetohydrodynamics, (2009), 45 (1), pp. 111-126.
  9. Dousset, V., Pothérat, A., Numerical simulations of a cylinder wake under a strong axial magnetic field, Phys. Fluids, (2008), 20, 017104, doi.org/10.1063/1.2831153.
  10. Muck, B., et al., Three-dimensional MHD flows in rectangular ducts with internal obstacles, J. Fluid Mech., (2000), 418, pp. 265-295.
  11. Frank, M., et al., Visual analysis of two-dimensional magnetohydrodynamics, Phys. Fluids, (2001), 13, pp. 2287-2295.
  12. Alboussiere, T., et al., Quasi-2d MHD turbulent shear layers, Exp. Therm. Fluid Sci., (1999), 20, pp. 19-24.
  13. Kolesnikov, Y. B., Tsinober, A. B., Experimental investigation of two-dimensional turbulence behind a grid, Fluid Dyn., (1974), 9, pp. 621-624.
  14. Moreau, J., Sommeria, R., Electrically driven vortices in a strong magnetic field, J. Fluid Mech., (1988), 189, pp. 553-569.
  15. Dearing, S. S., et al., Flow control with active dimples, The Aeronautical Journal, (2007), 111, pp. 705-714.
  16. Lienhart, H., et al., Drag reduction by dimples? A complementary experimental/numerical investigation, Int J Heat Fluid Flow, (2008), 29(3), pp. 783-791.
  17. Luo, Y. H., et al., Advances of drag-reducing surface technologies in turbulence based on boundary layer control, J. Hydrodyn., (2015), 27, pp. 473-487.
  18. Ge, M., et al., Y. Drag reduction of wall bounded incompressible turbulent flow based on active dimples/pimples, J Hydrodyn, (2017) 29, pp. 261-271, doi.org/10.1016/S1001-6058(16)60736-9
  19. Bogdanovic-Jovanovic, J., et al., Experimental and numerical investigation of flow around a sphere with dimples for various flow regime, Thermal Science, (2012), 16 (4), pp. 1013-1026.
  20. Stieger, R. D., Hodson, H. P., Reynolds Stress measurement with a single component Laser-Doppler anemometer, Proceedings, The 16th Symposium on Measuring Techniques in Transonic and Supersonic Flow in Cascades and Turbomachines, Cambridge, UK, 2002.