this is my geometry, its a storm water trap with an internal and external chamber. the bottom part of the internal chamber has a basket (the brown and green part, the brown part is solid since i want to simulate the basket as half full. the green part is my porous media volume)

in fluent I am putting the following parameters:

Type: Pressure-based

Velocity Formulation: Absolute

Time: Transient

gravity -9.81

VOF multiphase model

N of Eulerian Phase: 2

Formulation: Explicit

Interface Modelling: Sharp

k-epsilon realizable turbulence model

Phase 1: air

Phase 2: water

Surface tension: 0.072 constant

cell zone conditions

i have got the values for porous media from experimental work, plotting pressure against velocity as per Workbench guide.

Boundary Conditions:

Water Inlet (velocity-inlet type)

V: 0.45 m/s

Initial Pressure: 0

TKE: 1

Epsilon: 1

Phase 2 fraction: 1

Outlet (pressure outlet)

top (pressure outlet)

Solution Methods:

Pressure-Velocity Coupled (i have tried PISO as well)

Pressure: PRESTO!

Momentum: Second Order Upwind

Volume Fraction: Compressive

TKE: First Order Upwind

Turbulent Dissipation Rate: First Order Upwind

Transient Formulation: First Order Implicit

Solution Control:

Flow Courant: 200

Eexplicit RF

Momentum: 0.3 (i have tried the default as well)

Pressure: 0.3

Under RF

Density: 1

Body Forces: 0.5

TKE: 0.6

TDR: 0.6

Turbulent Viscosity: 0.5

Discrete Phase: 0.9

std Initialization from inlet

Time step size: 0.001(I have tried 0.01 as well)

N of time step: 1000000

would be great if you could help.

Thanks

Ikhlass