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 March 26, 2012, 00:45 the calculation of gradient #1 Member   zakir Join Date: Nov 2011 Posts: 43 Rep Power: 5 hello everybody From 10.1.1.3 Control Volume Gradients of the CFX-Sover Theory Guide ,I know that: ()=*(n) wheren is the outward surface vector at ip,V is the volume of the control volume. We can use the utility name USER_GETVAR to obtain the gradient we interest.what I want to know is how it calculate the gradient.What kind of algorithm does it use?Is it as the formulation above? I have a source term like this: source=-(A) where is the value of the variable at the cell faces f, and A is the face area vectors How can I implement it with fortran or something else? Thank you very much! zakir Last edited by zakir hussain; March 26, 2012 at 01:21.

 March 31, 2012, 23:34 #2 Member   zakir Join Date: Nov 2011 Posts: 43 Rep Power: 5 hello everyone I hope I can get help from you. I have a source term like this: source=-(A) where is the value of the variable at the cell faces f, and A is the face area vectors How can I implement it with fortran or something else? Thank you very much! zakir

 April 1, 2012, 06:53 #3 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,665 Rep Power: 84 What is the sum over? All the faces of the conttrol volume? What is the purpose of the source term? I cannot see its physical significance.

 April 2, 2012, 09:33 #4 Member   zakir Join Date: Nov 2011 Posts: 43 Rep Power: 5 yes,the sum over represents all the faces of the control volume.Considering the conservation I should solve the divergence of phi what I use as an source term of poisson equation through Gauss's law ,like =(A) Thank you for your help! zakir