[rahulksoni]

Dear Foamers

I am running a multiphase case with two solvers as mentioned. The phases are air, water, light density solids and high density solids. In the case of multiphaseInterFoam solids are assumed as liquid phase of similar densities.

My doubt arises at the moment I set the inlet conditions:
For multiphaseInterFoam I set fractional inlet values of all phases in 0/alpha.* files. e.g. for water as:

	inlet
	{
		type		fixedValue;
		value		uniform 0.85;
	}

Then, in file 0/U the total flow rate is set as:

	inlet
	{
		type			flowRateInletVelocity;
		volumetricFlowRate	0.001354;
	}

Now, it is obvious that, if I know the total inlet flow rate and fraction value of each phase then individual phases inlet flow rates and thereafter, inlet velocities (as inlet section area is defined) can be computed.

However, I have played with the various combination of inlet conditions for the case of multiphaseEulerFoam, but only one is working, which is described here:
In this case, I have to define the phases fraction in 0/alpha.* files as:

	inlet
	{
		type			fixedValue;
		value			0.92;	
	}

as well as the individual flow rates in 0/U.* files as:

	inlet
	{
		type			flowRateInletVelocity;
		volumetricFlowRate	1250E-6;	
	}

Now, this leads to confusion. I am defining the individual phase fraction as well as their individualistic flow rates at the inlet, which may contradict with each other in the case of incorrect calculations. For example, lets say the phase fraction are 0.1 0.2 0.4 0.3. Now, for total inlet flow rate of 1 m3/s, the right calculation for individualist flow rates should results into 0.1 0.2 0.4 0.3 m3/s, respectively. What if I put deviated values in the 0/U.* files. Whether, multiphaseEulerFoam will complain that the flow rate composition is not matching with the phase fractions given or it will calculate the fresh values.

In simplicity, my question is what OpenFoam is doing in case of multiphaseEulerFoam, which values are actually being considered, in 0/alpha.* files or 0/U.* files?


P.S.: Doubtful on first option (i.e. of 0/alpha.* values being sole and primary) as it will require total flow rate value which I am not providing anywhere as I did in 0/U file in multiphaseInterFoam case.

Regards

Rahul K Soni
Scientist, CSIR, India