*3.4. Cavitation Model*

The geometric model is based on watershed model with different valve opening under profile E. The two-phase flow material is set as water-liquid and water-vapor in the material library of the system (The simulation parameters are listed in Table A1). For the space discretization of the governing equations, simple algorithm is used to couple the velocity and pressure. The pressure term discretization format is PRISTO! In other terms, the second-order upwind model is used to simulate the river basin grid model with different openings in fluent. In LiquidlensTMLLG4 ultra-pure water treatment system, the inlet pressure is more than 500 kPa, and the outlet pressure ranges from *pout* = 100 kPa to *pout* = 500 kPa. That is to say, the maximum pressure difference between the two ends of the diaphragm valve in the system is about 400 kPa. Therefore, the simulated inlet is set as *pin* = 500 kPa pressure inlet, and the outlet is set as *pout* = 100 kPa pressure outlet.
