solving the momentum equation in UEqn.

callahance · June 12, 2012, 09:15

I have a general question,

in the UEqn in interFoam, the momentum equation is solved. If my momentum predictor is "no", then the surface tension force (fvc::interpolate(interface.sigmaK())*fvc::snGrad( alpha1) ) wont be considered in solving the equation.
On the other side, this surface tension force is considered in the pEqn. when calculating the flux phi = phiU + ... My question is : i wanted to add a term to the surface tension and i did that by adding it to the pEqn. The results are not so good. Is it not better to turn the momentumPredictor to "yes" and add this term to the surface tension in the UEqn. ?

Thanks in Advance

callahance · June 13, 2012, 07:27

i just added the term in the UEqn. und there were totally different results. Moreover, multiplying the surface tension term in the pEqn. shows very different results by changing the mesh resolution (high mesh resolutions give very strange curvatures on the interface). Unfortunatly, i need this term to be added in order to get the right surface tension (especially with very low cap. flows e.g. static droplets)

I'll see how can i define this force.
Any suggestions will be appreciated.

sahas · October 18, 2012, 09:38

I am interesting in this question too.
As I can see there are bad results with modeling of jet breakup with OF2 whereas with OF1.5 all is good

June 12, 2012, 09:15	solving the momentum equation in UEqn.	#1
callahance Member Join Date: Mar 2012 Posts: 51 Rep Power: 14	I have a general question, in the UEqn in interFoam, the momentum equation is solved. If my momentum predictor is "no", then the surface tension force (fvc::interpolate(interface.sigmaK())*fvc::snGrad( alpha1) ) wont be considered in solving the equation. On the other side, this surface tension force is considered in the pEqn. when calculating the flux phi = phiU + ... My question is : i wanted to add a term to the surface tension and i did that by adding it to the pEqn. The results are not so good. Is it not better to turn the momentumPredictor to "yes" and add this term to the surface tension in the UEqn. ? Thanks in Advance

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June 13, 2012, 07:27		#2
callahance Member Join Date: Mar 2012 Posts: 51 Rep Power: 14	i just added the term in the UEqn. und there were totally different results. Moreover, multiplying the surface tension term in the pEqn. shows very different results by changing the mesh resolution (high mesh resolutions give very strange curvatures on the interface). Unfortunatly, i need this term to be added in order to get the right surface tension (especially with very low cap. flows e.g. static droplets) I'll see how can i define this force. Any suggestions will be appreciated.

October 18, 2012, 09:38		#3
sahas Member Alexander Join Date: Mar 2009 Posts: 49 Rep Power: 17	I am interesting in this question too. As I can see there are bad results with modeling of jet breakup with OF2 whereas with OF1.5 all is good