# How do we write code for mean of reynolds stress tensor?

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 June 4, 2019, 05:38 How do we write code for mean of reynolds stress tensor? #1 New Member   VL Srinivas Join Date: Jan 2017 Posts: 4 Rep Power: 7 In TKE equation, the production term consists of reynolds stress tensor multiplied by strain rate ? The production term in tensor form = - *dU_i/dx_j ; here u=fluctuating component; U= mean component; d=partial derivative operator While writing code for the TKE equation, do I have to add all the 9 components of the stress tensor and then average it over time ? Production term: u'u' dU/dx + u'v'dU/dy + u'w'dU/dz + v'u'dV/dx + v'v'dV/dy + v'w'dV/dz + u'w'dW/dx + v'w'dW/dy + w'w'dW/dz where U= U(x,y,z) and u'= u'(x,y,z,t) Is this representation correct?

June 4, 2019, 09:51
#2
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Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
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Yes the summation is correct. You do not need to time average because all the variables are already averaged. You can take the time-average. You'll just find out it doesn't do anything.

Maybe you got lazy and dropped the notation but if <> represents reynolds averaging then you should have:

Quote:
 Production term: dU/dx + dU/dy + dU/dz + dV/dx + dV/dy + dV/dz + dW/dx + dW/dy + dW/dz

 June 4, 2019, 10:12 #3 New Member   VL Srinivas Join Date: Jan 2017 Posts: 4 Rep Power: 7 Thank you for the prompt reply. I will do that. Regarding the <> for every element, I forgot to put that.

 Tags programming, reynolds stress tensor, tke budget