How define Delta y(or x) between two neighbor cells for boundary condition ?

rapierrz · March 1, 2015, 10:41

Hi friends,

I want to add a boundary condition with below equation :

a*grad(phi)+b*grad(T)=0 at wall. a,b are constant and phi,T is scalarField.

grad(phi) is (phi-oldTime(phi))/delta y

How i can define delta y between two neighbor cells?

zfaraday · March 3, 2015, 13:20

I'm not sure if I understood well what you need, but if the delta you are referring is the face-center to cell-center distance you have to use the expression delta()

rapierrz · March 4, 2015, 00:00

Hi Alex,

I want to calculate the space between mesh near the upper wall of a chanel

and it's neighbor cell.

for example : (T-oldTime(T))/y2-y1;

y1=y position of mesh near the wall

y2=y position of mesh near the Previous mesh.

thank you,

kuangwulee · March 6, 2022, 06:49

Hello Rapierrz, have you found the answer to this? I need to calculate the distance between mesh points, for a self-defined variable, too.
Thanks in advance!

wuicylucy · March 15, 2022, 22:30

Thank you for your very good and helpful article. The information in the article will help me a lot

March 1, 2015, 10:41	How define Delta y(or x) between two neighbor cells for boundary condition ?	#1
rapierrz Senior Member Hesam Join Date: Feb 2015 Posts: 139 Rep Power: 11	Hi friends, I want to add a boundary condition with below equation : agrad(phi)+bgrad(T)=0 at wall. a,b are constant and phi,T is scalarField. grad(phi) is (phi-oldTime(phi))/delta y How i can define delta y between two neighbor cells?

March 3, 2015, 13:20		#2
zfaraday Senior Member Alex Join Date: Oct 2013 Posts: 337 Rep Power: 21	I'm not sure if I understood well what you need, but if the delta you are referring is the face-center to cell-center distance you have to use the expression delta() __________________ Web site where I present my Master's Thesis: foamingtime.wordpress.com The case I talk about in this site was solved with chtMultiRegionSimpleFoam solver and involves radiation. Some basic tutorials are also resolved step by step in the web. If you are interested in these matters, you are invited to come in!

March 15, 2022, 22:30		#5
wuicylucy New Member wuicylucy Join Date: Mar 2022 Posts: 1 Rep Power: 0	Thank you for your very good and helpful article. The information in the article will help me a lot __________________ wordle solver tiny fishing

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March 4, 2015, 00:00		#3
rapierrz Senior Member Hesam Join Date: Feb 2015 Posts: 139 Rep Power: 11	Hi Alex, I want to calculate the space between mesh near the upper wall of a chanel and it's neighbor cell. for example : (T-oldTime(T))/y2-y1; y1=y position of mesh near the wall y2=y position of mesh near the Previous mesh. thank you,

March 6, 2022, 06:49		#4
kuangwulee New Member Kuang-Wu Lee Join Date: Aug 2020 Posts: 2 Rep Power: 0	Hello Rapierrz, have you found the answer to this? I need to calculate the distance between mesh points, for a self-defined variable, too. Thanks in advance!