Grid Size Independency in Discrete Phase Model (DPM)

Grid Independence Study in DPM

In numerical studies, the governing equations are discretized and rewritten in each cell.

To have an exact CFD solution, we must generate an appropriate meshgrid to accurately capture variables value in each cell.

The mesh generated in Sound Generation (Acoustic) on Audi Car projectA grid independence study should be done to avoid any possible divergence or wrong solution. Therefore, we need to perform a mesh grid with different sizes while monitoring an important parameter as a result. As the parameter value fluctuation gets into an acceptable range, the solution becomes independent of the mesh grid. The following plot shows the grid independence study carried out in the paper “Attenuation of vibration in boring tool using spring controlled impact damper.”

From another perspective, we are not allowed to decrease the size of elements too much because it can cause an error in the simulation itself. Additionally, there is another limitation to the Discrete Phase Model. A very small grid would also disrupt, as discussed in the ‘ DPM overview’ article, the volume fraction of particles cannot be more than 10-12 % because interactions between the particles or bubbles are neglected in the Lagrangian model.

On an element scale, it should be considered that the cell size must be ten times the diameter of the parcel in, at least.