CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM

interfoam solver and contact angle

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   July 18, 2016, 12:55
Default interfoam solver and contact angle
  #1
New Member
 
Jun Zhang
Join Date: Jan 2014
Posts: 11
Rep Power: 5
bigfeather is on a distinguished road
Hi All

I am using interfoam solver to simulate droplet wetting on a surface. As a first step, I did a benchmark case to validate the result. However, I found that there is a discrepancy for the final static droplet shape. For example, I defined the static contact angle as 44 degree, but the final shape of droplet gives the contact angle as 47.4 degree. Consequently, the contact base radius is less than the corresponding theoretical result. The error is about 3%, and this error is independent of mesh sizes.

Anyone has met this problem before?

Best,
Kris
bigfeather is offline   Reply With Quote

Old   July 19, 2016, 02:32
Default
  #2
Member
 
Vignesh
Join Date: Oct 2012
Location: Darmstadt, Germany
Posts: 63
Rep Power: 6
vigneshTG is on a distinguished road
Hi,

I think thats the best you can get with interfoam !! What is the size of droplet ? Are you talking about the equilibrium shape of spreading drop (under zero gravity) ?
__________________
Thanks and Regards

Vignesh
vigneshTG is offline   Reply With Quote

Old   July 19, 2016, 10:31
Default
  #3
New Member
 
Jun Zhang
Join Date: Jan 2014
Posts: 11
Rep Power: 5
bigfeather is on a distinguished road
Quote:
Originally Posted by vigneshTG View Post
Hi,

I think thats the best you can get with interfoam !! What is the size of droplet ? Are you talking about the equilibrium shape of spreading drop (under zero gravity) ?
Hi Vignesh

The size of drop is micrometer or sub-micrometer. Yes I considered the equilibrium shape of spreading drop under zero gravity.

So you think there are some inherent numerical errors with interFoam?

best,
Kris
bigfeather is offline   Reply With Quote

Old   July 20, 2016, 06:17
Default
  #4
Member
 
Vignesh
Join Date: Oct 2012
Location: Darmstadt, Germany
Posts: 63
Rep Power: 6
vigneshTG is on a distinguished road
I tried using interfoam for capillary flow problems and i figured that it is not accurate !! There are several modified versions of interfoam like interSSFoam, sclsvoffoam .... you can try these and see if it fits !!

I tested sclsvoffoam for the equilibrium drop and other benchmark problems and it is quite accurate in these cases.
__________________
Thanks and Regards

Vignesh
vigneshTG is offline   Reply With Quote

Old   July 20, 2016, 09:55
Default
  #5
Senior Member
 
Saideep
Join Date: Apr 2015
Location: INDIA
Posts: 165
Rep Power: 3
Saideep is on a distinguished road
Hi Kris and Vignesh;

Maybe an other point to consider is the way you post-process in order to find the interface curvature.

In Paraview, I generally use a 0.5 contour of alpha1 (define this as my interface) and then try to fix a sphere at the interface in order to determine the radius and thereby the contact angle. We must not forget that the volField values of alpha fraction are being interpolated over an artificial contour to represent the interface.

Maybe could you explain how are you calculating the contact angle?

Saideep
Saideep is offline   Reply With Quote

Old   July 20, 2016, 11:33
Default
  #6
Member
 
Vignesh
Join Date: Oct 2012
Location: Darmstadt, Germany
Posts: 63
Rep Power: 6
vigneshTG is on a distinguished road
Quote:
Originally Posted by Saideep View Post
Hi Kris and Vignesh;

Maybe an other point to consider is the way you post-process in order to find the interface curvature.

In Paraview, I generally use a 0.5 contour of alpha1 (define this as my interface) and then try to fix a sphere at the interface in order to determine the radius and thereby the contact angle. We must not forget that the volField values of alpha fraction are being interpolated over an artificial contour to represent the interface.

Maybe could you explain how are you calculating the contact angle?

Saideep
Hi Saideep,

In the case of equilibrium shape of planar drop, i calculate the base length as the difference between the minimum and maximum location of X. So far, i have not measured contact angle in the simulations .... but i think, you take the cosine inverse of the dot product between unit normal to wall and interface normal in the patch. Pick the value of theta where alpha is close to 0.5 or interpolate the value !!
__________________
Thanks and Regards

Vignesh
vigneshTG is offline   Reply With Quote

Old   July 20, 2016, 12:03
Default
  #7
New Member
 
Jun Zhang
Join Date: Jan 2014
Posts: 11
Rep Power: 5
bigfeather is on a distinguished road
Quote:
Originally Posted by Saideep View Post
Hi Kris and Vignesh;

Maybe an other point to consider is the way you post-process in order to find the interface curvature.

In Paraview, I generally use a 0.5 contour of alpha1 (define this as my interface) and then try to fix a sphere at the interface in order to determine the radius and thereby the contact angle. We must not forget that the volField values of alpha fraction are being interpolated over an artificial contour to represent the interface.

Maybe could you explain how are you calculating the contact angle?

Saideep
Hi Saideep,

I did in the same way as you described. Pick up the points with the alpha of 0.5, and then fit the interface to a spherical cap. The contact angle is measured at the surface.

Have you validated the results for the equilibrium droplet on surface? how is your result?

Best,
Kris
bigfeather is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
error in contact angle and calculation of pc with interFoam Saideep OpenFOAM Running, Solving & CFD 4 March 22, 2016 10:38
solved: contact angle correction in interFoam rcastilla OpenFOAM Bugs 24 March 2, 2016 14:43
Dynamic contact angle calculation in multiphaseInterFoam rajeshchem OpenFOAM 2 January 31, 2014 08:52
dynamic contact angle udf returns no value to solver shiraz_man67 Fluent UDF and Scheme Programming 0 November 1, 2012 12:32
Theoretical background of formula for dynamic contact angle in interfoam sebastian_vogl OpenFOAM Running, Solving & CFD 3 June 22, 2009 12:25


All times are GMT -4. The time now is 18:43.