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Results doesn’t converge with fine boundary layer mesh |
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December 24, 2022, 18:21 |
Results doesn’t converge with fine boundary layer mesh
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New Member
Waru
Join Date: Apr 2022
Posts: 7
Rep Power: 4 |
Hi,
I'm stuck on this for a few weeks now, any help you can give is much appreciated. As shown below, a liquid coolant is poured onto a structure. Liquid coolant and air are the two phases. Initially, domain is only filled with air. I'm looking at the heat transfer between the liquid and the surface. See attached pictures of the setup "Boundry_conditions" & "geometry". This is a transient double precision simulation with PISO, Presto!, and Geo-reconstruct as the method. Turbulant model is K omega SST. Multi-phase is solved as a VOF with Implicit formulation, Implicit Body force and bounded second-order implicit transient formulation. To get an accurate heat transfer coefficient I am using fine boundary layers in my mesh (First height - 0.002mm, layers 7, transition ratio 0.3). Mesh has an orthogonal quality of 0.18 and an aspect ratio of 226 (I'm using Fluent Meshing watertight geometry). See attached "mesh"& "BL_mesh_zoom" to check my mesh. With these settings, all the parameters converge except for continuity at first. After several iterations, all the parameters started to diverge. I also ran a few simulations after increasing the first height of the boundary layer. With higher "First Height" results converge at first. But after around 100 iterations results start not to converge. I also checked the volume fraction of the domain at this point. This is the point where the secondary phase reaches the boundary layer. Finally, I ran a simulation without any boundary layers. Which ran without any issues, but gave wrong heat transfer results. Is this due to my boundary layer mesh? as you can see in the above picture, I don't have much room to add a lot of layers. can someone tell me what I am doing wrong here? How can I solve this issue? Thanks, Best regards, Waruna |
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Tags |
fluent meshing watertight, heat transfer, inflation layers, mesh 3d, vof multiphase |
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