Surface Yplus of a Cylinder

Nazrin
Nazrin Altair Community Member
edited June 11 in Community Q&A

Hello everyone,

I want to verify the surface y-plus of transient flow over cylinder. There are 2 situation of the Boundary (BL) mesh:

A: 1st BL height with y+ = 1 (viscous layer)
B: 1st BL with y+ = 50 (turbulent layer)

My question is: what is the expected y+ value of the cylinder's skin/surface during post processing for case A and B? Should it falls at the same region as preprocessing?

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Answers

  • ydigit
    ydigit
    Altair Employee
    edited June 7

    I do not completely understand your question, but if it concerns consistency between y+ calculated at pre and y+ visible in post, they should be somewhat consistent. Note that cylinder will have high velocity and low velocity flow, so the y+ is not going to be constant all round it (assuming BL in constant). 
    You should be able to visualize the Surface Y plus in HyperMesh CFD Post processing or HyperView or SimLab 

  • Nazrin
    Nazrin Altair Community Member
    edited June 7
    ydigit_21275 said:

    I do not completely understand your question, but if it concerns consistency between y+ calculated at pre and y+ visible in post, they should be somewhat consistent. Note that cylinder will have high velocity and low velocity flow, so the y+ is not going to be constant all round it (assuming BL in constant). 
    You should be able to visualize the Surface Y plus in HyperMesh CFD Post processing or HyperView or SimLab 

    For example, case B,

    Mesh 1st BL height of cylinder surface is 50 that falls in log-law region in pre-processing.

    1. So, during post-processing, should I expect the surface y+ of the cylinder in range of 30-300 (log law region)?

    2. What if the range falls in range of 2-150 (which combination of viscous, buffer and log law region)? Is it wrong?

  • acupro
    acupro
    Altair Employee
    edited June 11
    Nazrin_21804 said:

    For example, case B,

    Mesh 1st BL height of cylinder surface is 50 that falls in log-law region in pre-processing.

    1. So, during post-processing, should I expect the surface y+ of the cylinder in range of 30-300 (log law region)?

    2. What if the range falls in range of 2-150 (which combination of viscous, buffer and log law region)? Is it wrong?

    The turbulence models in AcuSolve are valid through the entire boundary layer - from Y+ = 1 to Y+ = 300.  Lower Y+ means more of the boundary layer profile is calculated with more mesh and higher computational cost, higher Y+ means more of the boundary layer profile is modeled.

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