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-   -   udf for ehd (http://www.cfd-online.com/Forums/fluent/46677-udf-ehd.html)

suribabu November 27, 2007 05:06

udf for ehd
 
I written udf for transport equation for solving charge density. in my udf

1 i solved for voltage using uds0 2 using above uds i solved for electric field define_adjust(domain,t) 3)using 2 I solved transport equation for charge density by using macro define_uds_flux(name,f,t,i)

IF u see this paper they described problem.u can see domain. ***for boundary conditions------------------- AT wire voltage =25kv at collector plate voltage = 0 remaining is symmetry BUT charge density on the wire is not constant. THIS will varry based on electric field. THIS is solved by iteratively . for this i written udf using define_profile() i supplied this profile to on the wire. but i did not got the results. PROFILE IS charge density on wire_new =old_charge+q*(1-alph) alpha is under relaxation q*=Ewire/Eonset Can any body give any advice on this .

suribabu November 28, 2007 01:50

Re: udf for ehd
 
hellow is there any one is there to discuss on ehd

ak6g08 May 26, 2009 16:16

Hi,

Ive seen this 2 years late:) but I would like to model EHD in fluent as well...I was wondering if you could give me any advice on how to write the UDF for the charge transport equation, I ask because there is also an ionic drift term...but the general scalar transport equation only has a diffusion, unsteady and convective flux term (and source term if you put one in). Any advice or references that you could point me too I would really appreciate.

Im sorry I cant be of any help

Thanks again
akour

johnwinter May 10, 2011 05:41

Hi all,

If any body has writted UDF for Guass law electric field or particle charge equation. Please share.

john


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