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Rayleigh-Benard convection in limited domains: Part 1 - Oscillatory flow
Full text linkTransition from the steady state to an oscillatory regime in three-dimensional limited aspect ratio boxes, filled with an incompressible fluid and heated from below, has been examined by direct numerical simulation. Two different physical problems have been considered: the first is related to a domain 3.5 X 1 X 2.1 filled with water at 70° C (Prandtl number 2.5); the second considers a domain 2.4 X1 X1.2 filled with water at 33°C (Prandtl number 5). The Rayleigh number has been varied from 20,000 to 80,000. A new procedure based on a statistical approach for ev aluation of the critical Rayleigh number for transition from steady state to oscillatory flow Ra has been introduced in order to reduce numerical errors and estimate the error bars. A systematic study for the determination of Ra has been conducted as a function of the geometries considered and the different flow structures observed
True transient vorticity-velocity method using preconditioned Bi-CGSTAB
No full textA fully implicit method for the solution of time-dependent Navier-Stokes equations written in terms of vorticity and velocity is presented. The field equations are discretized using second-order finite-difference technique and cast into a large sparse linear system. The numerical solution of the algebraic problem generated is obtained using a preconditioned Bi-CGSTAB method. The numerical method, developed mainly for the solution of true transient problems, also shows good stability behavior at high Rayleigh numbers. Sample results are presented for the window cavity at 10(4) less than or equal to Ra less than or equal to 10(8) and art oscillatory flow in liquid metal
Unsteady flow over geometrical discontinuity: numerical simulation of a fluid-structure interation in a deformable tank
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