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-   -   Time Varying Boundary Conditon (http://www.cfd-online.com/Forums/cfx/20987-time-varying-boundary-conditon.html)

ashish February 14, 2005 17:18

Time Varying Boundary Conditon
 
Hi all,

This bit is interesting.

I have a problem of time varying boundary condition. I have a function on as boundary condition which varies with time. Say function = sin(5*time). When i write it down in CEL it gives error that it is unable to compute the function "time"? Why so ? and if so .. how can i give a function varying with respect to time on boundary only. Many thanks, Ashish

Glenn Horrocks February 14, 2005 18:00

Re: Time Varying Boundary Conditon
 
Hi,

In the documentation, under the CEL expression language it describes the variables and their name for use in CFX. You will find the variable name for time is "t". Note it is case sensitive.

Glenn Horrocks

ashish February 14, 2005 21:31

Re: Time Varying Boundary Conditon
 
Hi Glenn, I have tried that option but it gives some error with a message that it is unable to compute "t". regards ashish

Rui February 15, 2005 07:21

Re: Time Varying Boundary Conditon
 
Hi,

In CEL expressions I use the variable "t" and it works. I think you get an error because the sine argument must have angular units, and when you create an expression sin(5*t) the argument unit is [s]. So you have to do sin(5*t*1 [rad]/1 [s]), or if you want the period to be 1/5 [s] : sin(5*t*2*pi [rad]/1 [s])

Regards,

Rui


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