Page 290 - Fundamentals of The Finite Element Method for Heat and Fluid Flow

SOME EXAMPLES OF FLUID FLOW AND HEAT TRANSFER PROBLEMS
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2.5 3 2 Mesh1
Mesh2
Local Nusselt number 1.5 1
Mesh3

0.5
0
5 10 15 20 25 30 35 40
Horizontal distance

Figure 9.21 Forced convection heat transfer downstream of a backward-facing step. Local
Nusselt number distribution on the hot wall for a Reynolds number of 500 on different
meshes

difference between all the three meshes was very small. Therefore, the second mesh was
used in all the calculations in order to save computational time, as the difference between
the local Nusselt number distribution of the finest mesh (third mesh) and the second was
very small. The small oscillations in the local Nusselt number distribution, especially on
the first mesh, was generated by the coarseness of the unstructured meshes.

(a) Re = 100, flow reattachment length from the inlet = 10.23

(b) Re = 200, flow reattachment length from the inlet = 14.63

(c) Re = 300, flow reattachment length from the inlet = 18.12

(d) Re = 500, flow reattachment length from the inlet = 22.92

Figure 9.22 Forced convection heat transfer downstream of a backward-facing step. Tem-
perature contours at different Reynolds numbers