Numerical Simulation

Computational Fluid Dynamics

Computational Fluid Dynamics (CFD) has grown into an appropriate tool for modelling and simulating as a cost-effective and valuable method to improve performance indices. CFD allows exact control of the boundary conditions and monitoring of the results with either high temporal resolution or high space resolution. On the other hand, the simulation procedure has to be validated by comparison with well-established theoretical and experimental results.

The intricate aspects of the pumping process of a gerotor pump make CFD the appropriate tool for modelling and simulation to provide insights into its flow characteristics. Because the instantaneous flow is rather dependent on the teeth contact, a new boundary condition of a virtual wall was developed, which allows simulation of the teeth contact in the interteeth radial clearances. This new boundary condition is utilized in a 3D model of the gerotor pump with mesh deformation and remeshing at every time step by means of a home-made ad-hoc code named viscous wall cell integrated into the computational fluid dynamics solver.

New Moving Wall Boundary Conditions to maintain the dynamic mesh quality with the gears motion. With this approach the mesh is moved at the two adjacent walls with the same velocity that keeps the mesh density and structure as the contact point zone moves. The video shows the new moving wall boundary condition in the inter-trochoidal profiles dynamic mesh of a mini gerotor pump. [see Reference 12]

The relative position of collaborative gears is changing but the dynamic mesh, that moves with contact point position thanks to the new moving wall boundary condition, keeps practically undistorted. The video shows the pressure distribution in the middle plane of a clearance disk in a mini gerotor pump. [see Reference 12]

Virtual contact points by using viscous wall cell new boundary condition (rotors with fixed centres) [see Reference 5]

Interteeth clearance variation by manufacturing tolerances simulation (virtual contact points of rotors with non-fixed centres) [see Reference 5]

Magnitud velocity contours with relief grooves effects in port border by restricted area