[soohoha]

hello
now i simulate condensation in plate heat exchanger
when simulate condensation, static pressure of the inlet go to minus
and due to the pressure reversal phenomenon, reverse flow occurs, and eventually the pressure field collapses, causing the flow to stop

my simulation setup is below

VOF
Explicit (Volume fraction cutoff : 1e-06)
Implicit body force
Interfacial Anti-Diffusion

Surface tension model: continuum surface stress

Phase change model : Lee model (r_eva=0, r_con = 10,000~100,000)

Turbulent model : k-omega SST
Low-Re corrections
Curvature Correction
Turbulence Damping Factor : 10

Inlet boundary condition
Mass flow inlet
T = 303.25K (T_sat = 303.15K)
Liq = G*(1-quality)
Gas = G*(quality)
Turbulent intensity : 10%
The commonly used formula, 0.16*(Re)^(-1/8), is applied to pipe flow, so the turbulent intensity should be adjusted upward to suit the analysis of a plate heat exchanger

Outlet boundary condition
T = 303.25K (T_sat = 303.15K)
Backflow Volume Fraction
From Neighboring Cell
I have tried using both, but the reverse flow is severe, causing instability in the internal pressure field

Numerical Scheme

Pressure-Velocity Coupling : SIMPLEC

Spatial Discretization
Gradient : Least Squares Cell Based
Pressure : Modified Body Force Weighted
When using PRESTO!, reverse flow makes pressure-velocity coupling difficult, so the more stable Modified Body Force Weighted method is used

Momentum : Second Order Upwind
Volume fraction : Geo-Reconstruct & CICSAM
I tried using Geo-Reconstruct, but due to the poor mesh quality of the analysis geometry, I switched to CICSAM to improve the convergence of the simulation
Turbulent Kinetic Energy, Specific Dissipation Rate, Energy : Second Order Upwind

Initial condition

In the analysis of plate heat exchangers, setting the initial conditions is challenging, so the velocity field is usually set to 0 and the volume fraction is also set to 0 to proceed with the simulation Turbulent Kinetic Energy
1e-08 [m^2/s^2]
Specific Dissipation Rate
1[/s]
Gas Volume Fraction
0
The initial temperature condition is set to 303.25, which is 0.1 degrees higher than Tsat = 303.15


Gas Volume Fraction initialization set to 0: Initially, the pressure field is formed, but as the flow progresses about halfway, condensation occurs, causing the static pressure to become negative and the flow to reverse
Gas Volume Fraction initialized to 0.779: The initial condition is set according to the inlet mass flux ratio, causing the static pressure to reverse
Gas Volume Fraction initialized to 1: The pressure reversal phenomenon occurs, and the reverse flow at the outlet in the Y-velocity direction is very strong

When there is no phase change, the results are reasonable compared to the experimental data. However, when phase change occurs, something impossible happens. Could I possibly get some help with this?