The major two phase flow regime in the micro tubes is the Slug flow regime. In this case there is one or few bubbles inside the channel. Hence, it is usually using surface tracking techniques for simulation of two-phase flow in micro tubes.
Surface tracking techniques
A variety of tracking surface methods are available including:
- Fluid Volume Method
- Level Set Method
- Front Tracking Method
- Phase Field Method
Among the above methods, the fluid volume method has been implemented in most CFD software applications for ease of implementation as well as the power to maintain mass consistency. In the OpenFOAM, there is the method of volume volume in the interFoam solver.
Simulating slug flow (Taylor bubble) with interFoam
In the present simulation, the bubble is moving under the difference in the contact angle among the various solid surfaces. A schematic of geometry is shown in the figure below.
In microtubes, surface forces are dominant over volumetric forces, so surface tension and viscous stresses predominate over inertial term. The flow inside the microtubes is assumed to be laminar. The contact angle of the joint is considered the constant and dynamic. The simulation result is seen at the bottom.