Dear all,
I am sorry to ask silly question. I am trying to simulate convective heat transfer in laminar flow by Using Ansys FLUENT 17.2.
Here is some details
•Plain tube
•Laminar flow (Velocity: 0.01209669 m/s)
•Working fluid: water liquid
•Internal diameter tube=15.88 mm
•Tube length =8.02 m (7.9 m is entrance region and 0.12 m is the test section)
•Inlet Temperature = 27 C
•Wall Temperature = 17 C
•Reference Temperature = Film Temperature = 22 C
•All Properties are calculated at Film Temperature
But the result is not good. The velocity and temperature profile should be parabolic.
Do you have any suggestion?
Thank you so much
Please change your mesh and do again. Now, your mesh is tetrahedron. I think, after 'inflation' , the mesh is changing. You follow this procedure:. 1. Set the mesh size and generate mesh, then you will get hecahedral mesh. 2. Set for inflation. Set inlet surface as body and boundary as edge of the inlet.
Thank you for your answer and also the sample. I am still trying your suggestion.
Anyone who have used Fluent can help you but you have to discuss first that where you are trying to take out these results at which line which section etc?
Thank you for the correction. The surface Nusselt number and pressure gradient is plotted on the wall of tube. The Static temperature and velocity (I am using y-velocity because the flow is in y-direction) are plotted in the cross section of tested area line 1 near the developing area and line 10 at the outlet.
Dear all,
I have tried the new mesh. The result is good enough but there are several problems:
1.The simulation does not get converged value.
2.The fluctuation of pressure is too high.
3.The velocity and temperature profile are better but they have not fully developed yet.
I attach the result.
Thank you.
Dear all,
I re simulate the case with modified mesh. I found that I input the wrong velocity so the previous simulation was not good. I found that The result now is close to theory.
Thank you so much for the help.
Dear Ariwibowo
The important parameters here are:
1- Mesh type and mesh dependence: the mesh type maybe tetrahedra or Automatic and the mesh independence is important to get the final number of mesh.
2- The inlet condition, which is so important to and the inlet velocity is calculated from Reynolds number.
3- The heat source value is mentioned as constant heat flux or constant wall temperature.
Good Luck
hello
when should we draw pipe with thickness? can u help me? i want to analyze cooper tube but i dont know draw a pipe with or without thikcness.
regard.
Dear Amirhossein Zabihi
It's depend on the complexity of the case. Sometimes, its difficult to make thin wall due to complexity on the case. In my case, I just adjust wall thickness in the fluent without drawing wall geometry. If you make fluid domain in the boundary of that domain can be set as wall then you can set the thickness in FLUENT.
If you wan to draw the wall you shoud make 2 domain. one is fluid and two is solid. You can set the thickness geometry on Spaceclaim or DM. But, you should notice that both domain should be connected (see the interface each domain) so heat transfer can be transferred from fluid to solid wall . If you do not aware with it. it's meaning less to draw the solid domain because heat can not transferred to solid domain.
Dear Teguh Hady Ariwibowo thanks for your answer. My geometry is cooper tube with 19.05 mm outer diameter and 17.8 inner diameter Which runs the spiral path . According to your description, Ithink its better to use thikcness in fluent.
regard.
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