how to understant the Solidification Drag Model in flow3d

Svenein · August 8, 2021, 00:55

As claimed in the user manual of flow3d, a darcy-type drag force is loaded to the mushy and solidified region. When Fs = 1, the Fd will be effectively infinite. In many literatures, there will be a small constant in the denominator to aviod division by zero.

Can anyone help to explain the "effectively infinite" and how flow3d deal with the "infinite"?

Fd= TSDRG*Fs^2/(1-Fs)^3;

koful · September 2, 2021, 12:27

Hello Svenein.

As far as I understand this equation is used only if local solid fraction is between coherent point and critical point which are used defined values.

below the coherent point Fd is assumed zero. critical solid fraction is 0.67 as default and TSDRG is 1. So Fd is like 12.5. If Fd is above this value, flow stops.

So I think if drag is above the critical Fd value, solver assumes that the flow stops (or drag is effectively infinite) and switches to a different model.

August 8, 2021, 00:55	how to understant the Solidification Drag Model in flow3d	#1
Svenein New Member Zhihao Ren Join Date: Aug 2021 Location: Chongqing, China Posts: 2 Rep Power: 0	As claimed in the user manual of flow3d, a darcy-type drag force is loaded to the mushy and solidified region. When Fs = 1, the Fd will be effectively infinite. In many literatures, there will be a small constant in the denominator to aviod division by zero. Can anyone help to explain the "effectively infinite" and how flow3d deal with the "infinite"? Fd= TSDRG*Fs^2/(1-Fs)^3;

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Adding New Drag Model to MPPICFoam	surajkvs	OpenFOAM Running, Solving & CFD	0	May 4, 2018 05:03
Foam::error::printStack after adding New Drag model	surajkvs	OpenFOAM Running, Solving & CFD	2	March 10, 2018 13:11
Solidification Shrinkage and Porosity Model	jk75	FLOW-3D	1	August 13, 2009 23:45
Solidification drag coefficient	atulverma	FLOW-3D	1	May 14, 2009 10:24
multiphase model and drag law	Yasmail AKARIOUH	FLUENT	0	April 29, 2008 08:44

September 2, 2021, 12:27		#2
koful Member Join Date: Jun 2014 Location: Turkey Posts: 58 Rep Power: 12	Hello Svenein. As far as I understand this equation is used only if local solid fraction is between coherent point and critical point which are used defined values. below the coherent point Fd is assumed zero. critical solid fraction is 0.67 as default and TSDRG is 1. So Fd is like 12.5. If Fd is above this value, flow stops. So I think if drag is above the critical Fd value, solver assumes that the flow stops (or drag is effectively infinite) and switches to a different model.