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Square Duct (square + duct)

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Engineering100%

Selected Abstracts

Mixed convection in a horizontal square duct with local inner heating

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2005
Koichi Ichimiya
Abstract Numerical analyses were performed for the effect of local inner heating on the mixing flow in a horizontal square duct. Three-dimensional governing equations were solved for Re = 100,Pr = 0.72, and six kinds of inner heating sizes in a duct, with insulated walls or uniform temperature walls. Local inner heating induced the local buoyancy force and produced four recirculating flows across a section in a thermally insulated duct. In a horizontal square duct with uniform wall temperature, the interaction of the buoyancy-induced flows by temperature difference between the fluid and the local inner heating, and between the fluid and the walls reduced the maximum intensity of the secondary flow. Two recirculating flows were generated in a downward region. Heat transfer was locally enhanced or depressed corresponding to the flow situation. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(3): 160,170, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20056 [source]

Time-linearized time-harmonic 3-D Navier,Stokes shock-capturing schemes

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2008
J.-C. Chassaing
Abstract In the present paper, a numerical method for the computation of time-harmonic flows, using the time-linearized compressible Reynolds-averaged Navier,Stokes equations is developed and validated. The method is based on the linearization of the discretized nonlinear equations. The convective fluxes are discretized using an O(,x) MUSCL scheme with van Leer flux-vector-splitting. Unsteady perturbations of the turbulent stresses are linearized using a frozen-turbulence-Reynolds-number hypothesis, to approximate eddy-viscosity perturbations. The resulting linear system is solved using a pseudo-time-marching implicit ADI-AF (alternating-directions-implicit approximate-factorization) procedure with local pseudo-time-steps, corresponding to a matrix-successive-underrelaxation procedure. The stability issues associated with the pseudo-time-marching solution of the time-linearized Navier,Stokes equations are discussed. Comparison of computations with measurements and with time-nonlinear computations for 3-D shock-wave oscillation in a square duct, for various back-pressure fluctuation frequencies (180, 80, 20 and 10,Hz), assesses the shock-capturing capability of the time-linearized scheme. Copyright © 2007 John Wiley & Sons, Ltd. [source]

A numerical-variational procedure for laminar flow in curved square ducts

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2004
P. M. Hatzikonstantinou
Abstract A new numerical method is presented for the solution of the Navier,Stokes and continuity equations governing the internal incompressible flows. The method denoted as the CVP method consists in the numerical solution of these equations in conjunction with three additional variational equations for the continuity, the vorticity and the pressure field, using a non-staggered grid. The method is used for the study of the characteristics of the laminar fully developed flows in curved square ducts. Numerical results are presented for the effects of the flow parameters like the curvature, the Dean number and the stream pressure gradient on the velocity distributions, the friction factor and the appearance of a pair of vortices in addition to those of the familiar secondary flow. The accuracy of the method is discussed and the results are compared with those obtained by us, using a variation of the velocity,pressure linked equation methods denoted as the PLEM method and the results obtained by other methods. Copyright © 2004 John Wiley & Sons, Ltd. [source]