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Select inflow under Compute From to tell FLUENT to use values at the inflow for the reference values. Check that the reference value for velocity is 1 m/s, temperature is 353 K, and coefficient of viscosity is 6.667e-7 kg/m-s as given in the Problem Specification. These reference values will be used to non-dimensionalize the distance of the cell center from the wall to obtain the corresponding y+ values. Click OK.
By using the following method, plot y+ values for wall-adjacent cells to check how they compare with the recommendation mentioned above.
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Make sure that Position on X Axis is set under Options, that 1 is the value next to X, and 0 is the value next to Y under Plot Direction. Recall that this tells FLUENT to plot the x-coordinate value on the abscissa of the graph. Select Turbulence... under Y Axis Function and select Wall Yplus from the drop down list under that. Since we want the y+ value for cells adjacent to the wall of the pipe, choose plate under Surfaces.
Click Plot.
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Under X Axis Function, pick Velocity... and then in the box under that, pick X Velocity. Finally, select outflow under Surfaces since we are plotting the velocity profile at the outflow. De-select plate under Surfaces.
Click on Axes... in the Solution XY Plot window. Select X in the Axis box. In the Options box select Major Rules to turn on the grid lines in the plot. Click Apply. Then select the Y in the Axis box, select Major Rules again, and turn off Auto Range. In the Range box enter 0.1 for the Maximum so that we may view the velocity profile in the boundary layer region more closely. Click Apply and Close.
Uncheck Write to File. Click Plot.
(Click picture for larger image)
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