[mejahan]

Dear CFX Experts,
I am trying to calculate the Time averaged WSS on a surface in a transient simulation.
I defined the following expression in CFX post:
areaAve(Wall Shear.Trnavg)@<target surface>
I expect that this would return a number independent from the selected time step, however, it changes when selecting different time steps.
I CFX-Pre, I did not specify the start/end time steps for the transient statistics.
I appreciate your advice in advance.
Thank you,

[aero_head]

Hello,

Have you seen this thread on the same topic?
Time Averaged Shear Stress

[mejahan]

Originally Posted by aero_head

Hello,

Have you seen this thread on the same topic?
Time Averaged Shear Stress

Hi Kira,
In the post you referred to, it was suggested to export the values to Excel and calculate the time averaged WSS. However, is seems to be for older CFX versions.
CFX can calculate the time averaged WSS if the transient statistics is activated in CFX-Pre. However, I assume that WSS.trnavg on a surface should not change when different time steps are selected in CFX-Post, since it is supposed to calculate an average value over the entire simulation time.
Any thoughts on this problem?

[ghorrocks]

Yes, that thread was before the transient statistics capability was available, or at least before I was aware of it

When you calculate areaAve(Wall Shear.Trnavg)@<target surface> for different time steps, doesn't the transient average function return the average of all time steps up to the one you select? So when you change time steps you are adding or removing time steps from the averaging process, so of course it is going to change.

Also: please do not post the same question multiple times. I have deleted the duplicate post. You only need to ask a question once.

[mejahan]

Originally Posted by ghorrocks

Yes, that thread was before the transient statistics capability was available, or at least before I was aware of it

When you calculate areaAve(Wall Shear.Trnavg)@<target surface> for different time steps, doesn't the transient average function return the average of all time steps up to the one you select? So when you change time steps you are adding or removing time steps from the averaging process, so of course it is going to change.

Also: please do not post the same question multiple times. I have deleted the duplicate post. You only need to ask a question once.

Thank you Glenn for your response
Therfore, I need to select the final time step to calculate the TrnAvg for the entire simulation.