a problem of udf
 

i wirte a udf for slip wall,using user-defined->funcions->interpreted,it can work.but,after i set all the solver and boudery condition, i gien the error message as fllowing when i set parameter in initialize menu. the error message is :

error: FLUENT received fatal signal(ACCESS_VIOLATION) 1 Note exact events leading to error 2 Save case/date under new name 3 Exit program and restart to continue 4 Report error to your distributor Error Object:()

please give me some advice

Re: a problem of udf
 

This is quite a common error message. Search this forum to find a lot of discussions about this.

It is usually connected to the access to memory locations by Fluent, as far as I know.

Make sure you have defined the correct number of UDS and/or UDM.

If you compute gradients in your UDF, be aware that at the beginning of the computation they are not defined, so, if you use the gradient of scalar i, it is better if you put a control like this:

if (NULL != THREAD_STORAGE(t,SV_UDSI_G(i)))

{ ...do what you have to do... }

else

{ ...use an alternative expression for what you need to compute... }

Regards,

Ale

Re: a problem of udf
 

Dear Ale: thank you for you help,now it can work well,my problem is to compute slip flow in micronozzle by using fluent.but there are two problem to be sloved: first: I set slip condition in Shear stress of Specified Shear under wall plant of boudary condtion menu. is it ringht?? second:these two box need stress(unit is pascla),but I only know the slip velosity,how can i translate it to stress?? BTW: could you please tell me you msn or email?? my msn is chuangxinzhao@hotmail.com thanks