## 2024/11/20, v3 
- Changed the gradient estimation in the pressure force for fluid and rigid particles in eq. 3.13 and 3.15 
to ensure that pressure forces due to own pressure always point in direction of smaller particle number density. 
Consequently, the normal force (eq. 3.20a and A.11.a) and the diagonal element (eq. A.5, A.8 and A.9) have been adapted accordingly
- The number of contacts computation (eq. 4.5) has been adapted to also consider particles as a contact if they have positive pressure.

## 2023/02/13, v2: 
- Changed the definition of f in section 4.2 from f(r) := 1/2 |r|^2 to f(p, λ) := 1/2 |r|^2

## 2023/02/6, v1: 
Authors version of the manuscript that was published at Computer Graphics Forum 2023.