Eulerian multiphase air-particles
 

I am using the Eulerian multiphase model to simulate an air pressure wave that hits a cloud of particles. The geometry consist of a duct with a pressure outlet box in the end. The pressure wave starts in the beginning of the duct and the particles are located about in the middle of it. I have used field functions to define the volume fraction of the particles so that they form a half sphere along the bottom of the duct.
Field function:(sqrt(pow($$Position[0]-2,2)+pow($$Position[1]+0,2)+pow($$Position[2]+0.25,2))<0.25)?0.02:0

What I want to happend in the simulation is that the pressure wave lifts the particles.

My problem is that I always get the error:

A floating point exception has occurred: floating point exception [Invalid operation]. The specific cause cannot be identified. Please refer to the troubleshooting section of the User's Guide.
Command: RunSimulation
CompletedCommand: RunSimulation
In: []
error: Server Error

I also can´t get any coupling between the particles and the pressure wave; the particles don´t move when the pressure wave hits them. The pressure wave on the other hand is affected by the particles i.e. swirls are formed.

I am very grateful for any help I can get, really need it!