I already understand how this force is set up to be able to output. But I have a question or conjecture:This force can only output the force that the fluid exerts on the side wall. What I understand is that the force here is the force of the fluid on the solid side wall calculated by the DBC boundary condition.

If I want to output the impact force of the particles on the wall (that is, there is only many floating bodies in the model and no fluid exists), it should be the force calculated using a certain discrete element contact model instead of by the DBC boundary condition. I also tried to output and compare the results, and found that the force output by the existing version (the force of the floating body particles on the side wall) is relatively small. In other words, the existing version does not support the force output of solid particles on the side wall. I don't know if I understand correctly, Can you give me some guidance or advice?

• When you use compute forces you extract the forces of the fluid. This means that if you drag a square in 2D, positive x-direction, you will see force fluid is negative in x-direction from DualSPHysics. This is because what is extracted is how "the fluid is acting on the boundary".

And this force contribution only includes the fluid.

If you have a case with no fluid particles, but a lot of floating squares, then ForceFluid = 0. Here you have to use FloatingInfo to get the force value out for each floating object. For the wall you have to use Chrono/DEM.

Kind regards

• @Asalih3d Thanks very much. I understand what you mean, but what I need is not the force of each floating object, but the force of the wall (some floating body acts on the wall, but which floating body is unknown)，and the wall is a kind of boundary defined by mkbound. What should I do to get the force of the wall.

• You can use Chrono to get the forces on the wall of the floating objects hitting the wall.

Kind regards

• Can you tell me how to get the force from FloatingInfo files? I only see the velocity value and angular velocity value.

Kind regards

Tom

• Sorry, maybe you mean we can get the force value by equation f=ma? Right

• You have to execute ComputeForces.exe (post-processing tool)

Example for win: %computeforces% -dirin %diroutdata% -onlymk:20 -viscoart:0.1 -savecsv %dirout2%/_ForceBuilding

• I think this may be a way to get the force which applied to the wall by the float. As far as I understand, the force on the wall calculated by this code can only output the force of the fluid on the wall. If you want to output the impact force of the floating body on the wall, you should do a certain amount of your own development.

• Hi, Alex

I am very sorry to reply to you so late. I understand and thank you for the approach.

Thank you so much

Best regards

Tom

• Hi, YuanTangjin

It is possible to obtain the force received by the wall according to the method described by Alex.

I make it .Here is my code.

set dirout2=%dirout%\forces

%computeforces% -dirin %diroutdata% -onlymk:11 -viscoart:0.1 -savecsv %dirout2%/_ForceBuilding

if not "%ERRORLEVEL%" == "0" goto fail

You can try it.

Kind regards

Tom

• @Tom Are you outputting the collision force of the floating body against the side wall? I also output this before, but the size of the force doesn't feel right, it's a little too small. I think you need to take a closer look here, how the code calculates the force