Date

2002

Author

Uygur, Ahmet Bilge

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A computational fluid dynamics (CFD) code based on direct numerical simulation (DNS) and the method of lines MOL approach developed previously for the solution of transient two-dimensional Navier-Stokes equations for turbulent, incompressible, internal, non-isothermal flows with constant wall temperature was applied to prediction of turbulent flow and temperature fields in flows dominated by forced convection in circular tubes with strong heating. Predictive ability of the code was tested by comparing its results with experimental data available in iiithe literature for air flowing upward in a vertical tube with heating rates causing significant property variation. Two entry Reynolds numbers were employed, with three different heating rates yielding conditions considered to be turbulent, sub- turbulent and laminarizing. Favorable comparisons were obtained between the predictions and measurements. Small discrepancies in the near wall region can be attributed to strong heating which induces significant variations of the gas properties. In an attempt to improve the performance of the code, a parallel algorithm of the code was developed and tested against sequential code for speed-up and efficiency. It was found that the same results are obtained with super-linear speed-up and efficiency. The code provides an algorithm for future DNS applications.

Subject Keywords

Computational fluid dynamics, Confined flows, Turbulent flows, Direct numerical simulation, Method of lines

URI

https://hdl.handle.net/11511/12584

Collections

Graduate School of Natural and Applied Sciences, Thesis