Problem with modelling heat exchanger(fluid-solid-fluid-solid)

RodriguezFatz · December 16, 2013, 09:21

Ok, where is the line located (regarding x-direction)? In the middle of your pipe?

samanpoura · December 16, 2013, 09:30

line start from the cennteral point of iner pipe and end on outer surface of outer pipe

RodriguezFatz · December 16, 2013, 09:37

Yes, but regarding x-direction?
Also, if you don't have periodic b.c. in x-direction: Where did you make the contour plot and what b.c. did you set for the inner (solid) pipe at the pipe's ends?

samanpoura · December 16, 2013, 09:41

can u give me a email and i send u cas and data?
i cant find the problem ):

RodriguezFatz · December 16, 2013, 10:50

Look at your velocity profile. This looks like a rectangular function. This can't work.

Your problem is, that
1) Your fluid mesh is much too coarse. You only have 10 gridpoints for a pipe flow that probably is turbulent.
2) You don't use a turbulence model.

-> Make the mesh much finer and use a turbulence model.

samanpoura · December 16, 2013, 17:36

thank u very much

December 16, 2013, 09:21		#21
RodriguezFatz Senior Member Philipp Join Date: Jun 2011 Location: Germany Posts: 1,297 Rep Power: 27	Ok, where is the line located (regarding x-direction)? In the middle of your pipe? __________________ The skeleton ran out of shampoo in the shower.

December 16, 2013, 09:37		#23
RodriguezFatz Senior Member Philipp Join Date: Jun 2011 Location: Germany Posts: 1,297 Rep Power: 27	Yes, but regarding x-direction? Also, if you don't have periodic b.c. in x-direction: Where did you make the contour plot and what b.c. did you set for the inner (solid) pipe at the pipe's ends? __________________ The skeleton ran out of shampoo in the shower.

December 16, 2013, 10:50		#25
RodriguezFatz Senior Member Philipp Join Date: Jun 2011 Location: Germany Posts: 1,297 Rep Power: 27	Look at your velocity profile. This looks like a rectangular function. This can't work. Your problem is, that 1) Your fluid mesh is much too coarse. You only have 10 gridpoints for a pipe flow that probably is turbulent. 2) You don't use a turbulence model. -> Make the mesh much finer and use a turbulence model. samanpoura likes this. __________________ The skeleton ran out of shampoo in the shower.

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December 16, 2013, 09:41		#24
samanpoura New Member saman poura Join Date: Dec 2013 Posts: 13 Rep Power: 13	can u give me a email and i send u cas and data? i cant find the problem ):

December 16, 2013, 17:36		#26
samanpoura New Member saman poura Join Date: Dec 2013 Posts: 13 Rep Power: 13	thank u very much