Free Surface Problem

talatgokcer · January 8, 2016, 18:17

Hello Everyone,

I want to make a simulation two phase ship flow simulation on OpenFoam. I did my test simulation on OpenFoam DTC tutorial. I generated a mesh on snappyHexMesh and run setFields. My initial free surface condition is not that i want. There are nonsense surface elevations. What shall i do in order to make it better?

Thanks

talatgokcer · January 8, 2016, 18:19

Here is my snapshot

freesurface.jpg

talatgokcer · January 8, 2016, 18:21

and my dict files

freesurface.zip

pbalz · January 9, 2016, 08:52

Hi,

this could be a mesh effect.
Is your alpha 0.5 contour perfectly flat?

Sometimes it can be beneficial to use a small offset in your setFields value, i.e. 0.245 instead of 0.244.

If this doesn't work try meshing with high aspect ratio cells (so "flat" cells, as in the DTCHull tutorial) at your water surface. This should yield a better z-wise resolution so that setFields picks the right cells.

talatgokcer · January 9, 2016, 10:04

Hi Pascal,

No, it's my 0.5 alpha contour unfortunately. I'm going to try your advices. However, in high aspect ratios snappyhexmesh is challenge. I should play refinement boxes for that. Thank you

January 8, 2016, 18:17	Free Surface Problem	#1
talatgokcer New Member talat gokcer Join Date: Nov 2015 Posts: 6 Rep Power: 11	Hello Everyone, I want to make a simulation two phase ship flow simulation on OpenFoam. I did my test simulation on OpenFoam DTC tutorial. I generated a mesh on snappyHexMesh and run setFields. My initial free surface condition is not that i want. There are nonsense surface elevations. What shall i do in order to make it better? Thanks

January 9, 2016, 08:52		#4
pbalz Member Pascal Balz Join Date: Feb 2015 Location: Germany Posts: 44 Rep Power: 12	Hi, this could be a mesh effect. Is your alpha 0.5 contour perfectly flat? Sometimes it can be beneficial to use a small offset in your setFields value, i.e. 0.245 instead of 0.244. If this doesn't work try meshing with high aspect ratio cells (so "flat" cells, as in the DTCHull tutorial) at your water surface. This should yield a better z-wise resolution so that setFields picks the right cells. __________________ Regards, Pascal

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January 8, 2016, 18:19		#2
talatgokcer New Member talat gokcer Join Date: Nov 2015 Posts: 6 Rep Power: 11	Here is my snapshot freesurface.jpg

January 8, 2016, 18:21		#3
talatgokcer New Member talat gokcer Join Date: Nov 2015 Posts: 6 Rep Power: 11	and my dict files freesurface.zip

January 9, 2016, 10:04		#5
talatgokcer New Member talat gokcer Join Date: Nov 2015 Posts: 6 Rep Power: 11	Hi Pascal, No, it's my 0.5 alpha contour unfortunately. I'm going to try your advices. However, in high aspect ratios snappyhexmesh is challenge. I should play refinement boxes for that. Thank you