I have a multiphase case (VOF) and simulated it using interFoam. Using ExtractBlock filter I have selected a patch I need and I have got the patch normals using GenerateSurfaceNormals filter.

My first question is how to define the force on the patch using the calculator filter. Does “p*Normals” work and give the force vector in Newton? I understand that the force is pressure times area, but I cannot see how to multiply pressure by the patch cell area and integrate it over the patch to get Fx and Fy.

Moreover for a single point on the patch, I need to plot the force x and y components and pressure over all time steps. How can I use filters to do it? Any help is greatly appreciated.
Cheer

Thanks very much for your response.
So I need to calculate the force making sure about the units which is fine but could you please let me know how I can get the patch cells area to integrate my calculations over the patch?
Re plot data over time, my problem is that I cannot select the points I need so that I can plot the point data over time. I have clipped and sliced my patch to get a line and I would like to select a point on the line and plot the results for that point over time but I couldn’t get it to work.

That is one way to do it, yes. It would be easier to read a line from a file if it is already defined somewhere. A simple .csv + TableToPoints would do the trick.

Okay thanks. I’ll give them a go. My patch is a bit complex so a bit hard to get the point coordinates but I guess the way you said is good if I can define points in a .csv file somehow.
Cheers Mathieu