Possible reason for particles out

Dear all

I want to model the interaction of a floating body with waves using DualSPHysics. I simulate the problem in a range of wave heights and periods. The problem was that by increasing the wave height, the results of the motion of the floating body became strange, like sinking (The body oscillates around e.g. -2 m). I checked the size of each parts and soon i found out that the size of each parts decreased as the time passed by. Then i checked the Run.out file and i observed that some particles leave the domain at some time instances. In other words, the depth of the flume decreased from 0.65 m to e.g. 061 m because about one tenth of particles left the boundary. I expected that by increasing the number of particles, I can overcome this problem, but increasing the number of particles lead to increase the ratio between the (total out particles/total number of particles).

Then I removed the floating body and i saw this behaviour again. In my case, the water depth is 0.65 m and the height of the wave tank is about 2 m. I don't have any problem with low waves (e.g. <5 cm), but when i increase the wave height to e.g. 10 cm, lots of particles leave the simulation domain. Does any one have an idea about this problem?

Best regards

Kaveh