Learning Forum

[AmirB]

Hello!nI want to create a variable that depends on itself in the previous time step. My variable is the concentration surface C(t+dt)= C(t)*(1-a*dt). Can anyone help me, please?nThanks in advance!n

[Surya Deb]

Hello, nI think you can do this in 2 different ways. n1st technique: Create an additional variable and store the value from previous time step. You can then use the Algebraic Equation for this AV.n You can create an expression to calculate the previous time step value like : prevTemp = Temperature -(Temperature. Time Derivative*dtstep). Check the link below to get more information as well. https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v211/en/cfx_ref/i1305073.html?q=time%20derivative%20celnn2nd technique: The other possible way could be to make use of Arithmetic Sum. You can create a monitor point and monitor the current value as well as the Arithmetic sum for the last 2 time steps. Then you can define an expression using probe functionality to subtract the 2 values to get your previous time step value. The above link will provide information on how to use probe CEL as well.nI hope this helps.nRegards,nSuryan

[AmirB]

Hello Surya!nThanks for your response it helps me. I followed the first technique, but I had a little problem, I can not find how to initialize my additional variable. Do you have any idea how I can initialize the additional variable, please?nBest regardsnAmirn

[zhanghao zhang]

Hello,could you tell me how to get flow rate at previous time step for use CEL in cfx?

I have completed the previous Pressure,but the flow rate I don't know.

Thank you