Recent content by overgift

Firstly I really feel so lucky to find this forum. Since I don't have a strong physics background but now dealing with many problems directly related to physics. I'm now doing some simulation in comsol and need to solve some PDEs. I'm using this PDE coefficient form in comsol. The equations...

Thank you for your post. It really helps a lot

Thanks a lot! Now I totally understand.

Thank you again for your help! ∂Tij/∂xj = ∂Ti1/∂x1 + ∂Ti2/∂x2 + ∂Ti3/∂x3 this I can understand, what I can't understand is stress is already the average amount of force,doesn't it already fit F=ma? so why take partial derivative, what does this mean?

Hi thank you for your kind reply. The equation writes: \rho*\ddot{ui}-\partialTij/\partialxj=0 uiis the volume displacement, T is stress.

I'm learning piezoelectricity right now and got an equation I can't understand. It writes the Newton's sencond law for the stresses in materials due to elastic and piezoelectric contribution. The equation is in the attachment. In this equation I'd like to ask what is the partial derivative...