Non-uniform 1st Layer Height at BL

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

Hi everyone,

I noticed that the 1st layer height of Boundary Layer is not uniform and not equal to the input value. 
Case: 2D mesh 
Input 1st layer height: 0.002653m
Edge layer input:
image

Result:
image

I believed this non-uniform 1st layer height contribute to the un-even total BL height that had been addressed 2 years ago which still exist till now.
(2D Meshing issues - HyperWorks CFD - Altair Products - Altair Community). 

This issue will affect:
1. Timestep size
2. The turbulence layer 30>y+>300 if I try to model at y+ = 30. The 1st layer height might fall in the buffer layer.

Is there any reason for this uneven 1st layer height? Attached is my .hmcfd file. 
*Please ignored the naming scheme of my file.

Tagged:

Best Answer

  • acupro
    acupro
    Altair Employee
    edited July 11 Answer ✓

    I wouldn't be too concerned about the variation affecting the results much - as AcuSolve is not CFL-limited, and the wall functions are valid through the entire boundary layer.  That being said, I agree this needs to be corrected with development, and I have submitted a ticket.  (I should have done that two years ago...)

Answers

  • acupro
    acupro
    Altair Employee
    edited July 11 Answer ✓

    I wouldn't be too concerned about the variation affecting the results much - as AcuSolve is not CFL-limited, and the wall functions are valid through the entire boundary layer.  That being said, I agree this needs to be corrected with development, and I have submitted a ticket.  (I should have done that two years ago...)

  • Nazrin
    Nazrin Altair Community Member
    edited July 11
    acupro_21778 said:

    I wouldn't be too concerned about the variation affecting the results much - as AcuSolve is not CFL-limited, and the wall functions are valid through the entire boundary layer.  That being said, I agree this needs to be corrected with development, and I have submitted a ticket.  (I should have done that two years ago...)

    I appreciate for the ticket you had submitted. TQVM!

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