Moving Mesh (Mesh Motion): Ram Pump

Ram Pump CFD Simulation

Description

In this project, a ram pump is simulated using ANSYS Fluent software. The simulation employs a mesh motion model with an angular velocity of 1 radian per second. Water enters the domain at a velocity of 1 m/s and is discharged at the outlet at atmospheric pressure.

Geometry & Mesh

The two-dimensional geometry of this project is produced using SpaceClaim software. The computational domain has a length of 220 cm and a height of 153 cm. The meshing is performed with ANSYS Meshing software using unstructured elements, and the total number of elements is 325,579.

Ram Pump CFD Simulation

Because the flow is incompressible, a pressure-based solver is selected, and the simulation is transient. The effect of gravity is taken into account as -9.81 m/s² along the y-axis.

For the turbulence modeling, the k-omega SST model is used. The mesh motion is applied to the left and right valves as a cell zone condition, with a rotational velocity of 1 rad/s. Regarding the boundary conditions, the inlet is defined as a velocity inlet with a velocity magnitude of 1 m/s, the outlet is defined as a pressure outlet with a gauge pressure of 0 Pa, and the walls are treated as stationary walls.

In terms of solution methods, the pressure–velocity coupling is handled with the Coupled scheme. For spatial discretization, a second-order scheme is used for pressure, second-order upwind for momentum, and first-order upwind for both the turbulent kinetic energy and the turbulent dissipation rate. The solution is initialized using the hybrid method.

Ram Pump Results

At the end of the simulation, the velocity and pressure fields can be examined. When both valves are half-closed, the resulting restriction increases the pressure inside the pipe. When one valve is fully open and the other is completely closed, all of the inlet fluid exits through the open side under the high pressure created there.