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Wall Distance y+
Again the reference grid was the basis for the investigations of the normalized wall distance y+. For this the wall nearest grid point was varied between y+ = 0.07 to y+= 7.
In the results (Fig. 6) a high sensitivity to the wall distance y+ is seen, with a widening of the boundary layer and modification of Tw, and hence uT. Depending on the model, at y+ « 1 these values achieve differences up to 2.5% compared to the reference computations. With further variations the differences exceed 25% quite fast. As the figure 7 shows, the behavior of the error in Cf is independent of the position in the boundary layer. y+ > 7 leads to divergence of the simulations or
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yplus Fig. 2 Flat plate — SAE model — graph of u+ /y+ with variations of grid inclination in the boundary layer at x = 1.021 and x = 4.124 |
unexpected results. The results shown all apply the default low-Re wall treatment and the use of wall functions were not examined.
