34 research outputs found
Forced Convection Heat Transfer from a Finite-Height Cylinder
[EN] This paper presents a large eddy simulation of forced convection heat transfer in
the flow around a surface-mounted finite-height circular cylinder. The study was carried out
for a cylinder with height-to-diameter ratio of 2.5, a Reynolds number based on the cylinder
diameter of 44 000 and a Prandtl number of 1. Only the surface of the cylinder is heated
while the bottom wall and the inflow are kept at a lower fixed temperature. The approach
flow boundary layer had a thickness of about 10% of the cylinder height. Local and averaged
heat transfer coefficients are presented. The heat transfer coefficient is strongly affected
by the free-end of the cylinder. As a result of the flow over the top being downwashed
behind the cylinder, a vortex-shedding process does not occur in the upper part, leading
to a lower value of the local heat transfer coefficient in that region. In the lower region,
vortex-shedding takes place leading to higher values of the local heat transfer coefficient.
The circumferentially averaged heat transfer coefficient is 20 % higher near the ground than
near the top of the cylinder. The spreading and dilution of the mean temperature field in the
wake of the cylinder are also discussed.The simulation was carried out using the supercomputing facilities of the Steinbuch Centre for Computing (SCC) of the Karlsruhe Institute of Technology. MGV has been partially supported by grant TRA2012-37714 of the Spanish Ministry of Economy and Competitiveness.GarcĂa Villalba, M.; Palau-Salvador, G.; Rodi, W. (2014). Forced Convection Heat Transfer from a Finite-Height Cylinder. Flow, Turbulence and Combustion. 93(1):171-187. https://doi.org/10.1007/s10494-014-9543-7S171187931Ames, F., Dvorak, L.: Turbulent transport in pin fin arrays: experimental data and predictions. J. Turbomach. 128(1), 71â81 (2006)Armstrong, J., Winstanley, D.: A review of staggered array pin fin heat transfer for turbine cooling applications. J. Turbomach. 110, 94 (1988)Breuer, M., Rodi, W.: Large eddy simulation of complex turbulent flows of practical interest. In: Hirschel, E. (ed.) Flow Simulation with High Performance Computers II, Notes on Numerical Fluid Mechanics, Vol. 52, pp 258â274. Vieweg, Braunschweig (1996)Chen, S., Sanitjai, S., Ghosh, K., Goldstein, R.: Three-dimensional vortex flow near the endwall of a short cylinder in crossflow: uniform-diameter circular cylinder. Appl. Therm. Eng. 49, 73â78 (2012)Delibra, G., Hanjalic, K., Borello, D., Rispoli, F.: Vortex structures and heat transfer in a wall-bounded pin matrix: LES with a RANS wall-treatment. Int. J. Heat Fluid Flow 31(5), 740â753 (2010)Denev, J.A., Fröhlich, J., Bockhorn, H.: Large eddy simulation of a swirling transverse jet into a crossflow with investigation of scalar transport. Phys. Fluids 21, 015101 (2009)Donnert, G.D., Kappler, M., Rodi, W.: Measurement of tracer concentration in the flow around finite-height cylinders. J. Turbul. 8, 33 (2007)Frederich, O., Thiele, F.: Turbulent flow dynamics caused by a truncated cylinder. Int. J. Heat Fluid Flow 32(3), 546â557 (2011)Fröhlich, J., GarcĂa-Villalba, M., Rodi, W.: Scalar mixing and largeâscale coherent structures in a turbulent swirling jet. Flow Turbul. Combust. 80, 47â59 (2008)Fröhlich, J., Rodi, W.: LES of the flow around a cylinder of finite height. Int. J. Heat Fluid Flow 25, 537â548 (2004)GarcĂa-Villalba, M., Fröhlich, J.: LES of a free annular swirling jetâDependence of coherent structures on a pilot jet and the level of swirl. Int. J. Heat Fluid Flow 27(5), 911â923 (2006)GarcĂa-Villalba, M., Li, N., Rodi, W., Leschziner, M.A.: Large eddy simulation of separated flow over a three-dimensional axisymmetric hill. J. Fluid Mech. 627, 55â96 (2009)Germano, M., Piomelli, U., Moin, P., Cabot, W.: A dynamic subgrid-scale eddy viscosity model. Phys. Fluids 3, 1760â1765 (1991)Hinckel, J.N., Nagamatsu, H.T.: Heat transfer in the stagnation region of the junction of a circular cylinder perpendicular to a flat plate. Int. J. Heat Mass Tran. 29(7), 999â1005 (1986)Hinterberger, C.: Dreidimensionale und tiefengemittelte Large-eddy-simulation von flachwasserströmungen. University of Karlsruhe (2004). Ph.D. thesisHölscher, N., Niemann, H.J.: Some aspects about the flow around a surface-mounted circular cylinder in a turbulent shear flow. In: Proceedings of 6th Symp. Int. Turbulent Shear Flows, ToulouseKrajnovic, S.: Flow around a tall finite cylinder explored by large eddy simulation. J. Fluid Mech. 676, 294â317 (2011)Lilly, D.: A proposed modification of the Germano subgrid-scale closure method. Phys. Fluids 4, 633â635 (1992)Morgan, V.T.: The overall convective heat transfer from smooth circular cylinders. Adv. Heat Tran. 11, 199â264 (1975)NiÄeno, B., Dronkers, A., HanjaliÄ, K.: Turbulent heat transfer from a multi-layered wall-mounted cube matrix: a large eddy simulation. Int. J. Heat Fluid Flow 23(2), 173â185 (2002)Palau-Salvador, G., GarcĂa-Villalba, M., Rodi, W.: Scalar transport from point sources in the flow around a finite-height cylinder. Environ. Fluid Mech. 11, 611â625 (2011)Palau-Salvador, G., Stoesser, T., Fröhlich, J., Kappler, M., Rodi, W.: Large-eddy simulations and experiments of flow around finite-height cylinders. Flow Turbul. Combust. 84, 239â275 (2010)Pattenden, R., Turnock, S., Zhang, X.: Measurements of the flow over a low-aspect ratio cylinder mounted on a ground plate. Exp. Fluids 39, 10â21 (2005)Pierce, C.: Progress-variable approach for large-eddy simulation of turbulent combustion. Stanford University (2001). Ph.D. thesisPopovac, M., Hanjalic, K.: Vortices and heat flux around a wall-mounted cube cooled simultaneously by a jet and a crossflow. Int. J. Heat Mass Transfer 52, 4047â4062 (2009)Rhie, C., Chow, W.: Numerical study of the turbulent flow past an airfoil with trailing edge separation. AIAA J. 21(11), 1061â1068 (1983)Rostamy, N., Sumner, D., Bergstrom, D.J., Bugg, J.D.: Local flow field of a surface-mounted finite circular cylinder. J. Fluids Struct. 34, 105â122 (2012)Sanitjai, S., Goldstein, R.J.: Forced convection heat transfer from a circular cylinder in crossflow to air and liquids. Int. J. Heat Mass Tran 47, 4795â4805 (2004)Sanitjai, S., Goldstein, R.J.: Heat transfer from a circular cylinder to mixtures of water and ethylene glycol. Int. J. Heat Mass Tran. 47, 4785â4794 (2004)Sparrow, E.M., Stahl, T.J., Traub, P.: Heat transfer adjacent to the attached end of a cylinder in crossflow. Int. J. Heat Mass Tran. 27(2), 233â242 (1984)Stone, H.: Iterative solution of implicit approximations of multidimensional partial differential equations for finite difference Methods. SIAM J. Numer. Anal. 5, 530â558 (1968)Sumner, D.: Flow above the free end of a surface-mounted finite-height circular cylinder: a review. J. Fluids Struct. 43, 41â63 (2013)Tsutsui, T., Igarashi, T., Nakamura, H.: Fluid flow and heat transfer around a cylindrical protuberance mounted on a flat plate boundary layer. JSME Ser. B 43(2), 279â287 (2000)Tsutsui, T., Kawahara, M.: Heat transfer around a cylindrical protuberance mounted in a plane turbulent boundary layer. J. Heat Tran. 128, 153â161 (2006)Tutar, M., Akkoca, A.: Numerical analysis of fluid flow and heat transfer characteristics in three-dimensional plate fin-and-tube heat exchangers. Num. Heat Tran. A 46, 301â321 (2004)Zhu, J.: Low diffusive and oscillationâfree convection scheme. Comm. Appl. Num. Meth. 7, 225â232 (1991)Zukauskas, A.A.: Heat transfer from tubes in cross-flow. Adv. Heat Tran. 8, 93â160 (1972
Discontinuous Galerkin and multiscale variational schemes for a coupled damped nonlinear system of Schr\uf6dinger equations
In this article, we study a streamline diffusion-based discontinuous Galerkin approximation for the numerical solution of a coupled nonlinear system of Schr\uf6dinger equations and extend the resulting method to a multiscale variational scheme. We prove stability estimates and derive optimal convergence rates due to the maximal available regularity of the exact solution. In the weak formulation, to make the underlying bilinear form coercive, it was necessary to supply the equation system with an artificial viscosity term with a small coefficient of order proportional to a power of mesh size. We justify the theory by implementing an example of an application of the time-dependent Schr\uf6dinger equation in the coupled ultrafast laser