# Visualizing Phases with Shan-Chen Multicomponent Model

Is there an “easy” way to visualize the phases e.g. with rho1 and rho2 instead of using the pressure as it is done in examples/multicomponent2D. Is it possible to produce vtk data (VTKDataWriter3D not vtk image vti) for 2D simulations if yes how.

Jens

pressure is calculated from rho1 and rho2 values… not sure what you mean. The pressure visualisation is the easiest method I know of.

Hi,
This part is a bit confusing in the example program. It uses the word “pressure”, but the thing which is plotted is really proportional to the density, which means, the program does what you want it to do. When you use BGK for incompressible fluid flow, the pressure is proportional to the density, which explains why the term “pressure” was used in the code. However, in multi-phase flows the pressure-density relation is more complicated. Therefore, it would be appropriate to use the word “density” when the program plots the density. We’ll change this in future versions of the code.

Hi,

I am still not sure about the second part of my original question:

Is it possible to produce vtk data (VTKDataWriter3D not vtk image vti) for 2D simulations? If yes how.

1. @ jonas: Thanks for the publication of OpenLB it is a nice tool to play with. How are the current plans on a new release?
2. unfortunately the multiphase Shan-Chen is not well documented in the UG, but there is some literature and the source code:-), but it is still hard and time consuming to dig in the source code, so hopefully there will be some more info in future versions of the UG.
3. pressure and density: Is the pressure right now: p_i=c_s^2rho_i=rho_i/3 ? So it is like partial pressure? But according to Sukop the pressure should be something like: p_i=rho_i/3+G/6Psi_i^2 with Psi_i=Psi_0*exp(-rho_o/rho_i). But looking through literature there are more than one functions for Psi and so more than one approximations for the EOS.
4. Am I right with my assumption for the current (forcedShanChenCouplingPostProcessor2D.hh) Psi function: Psi_i=rho_i ?

Jens