engleski

SIMULATION OF FREE-RISING BUBBLE WITH SOLUBLE SURFACTANT USING MOVING MESH FINITE VOLUME/AREA METHOD

In this study, flow simulation of the two-fluid system with sharp interface and soluble surfactants is performed using OpenFOAM, an object-oriented C++ library for simulations in continuum mechanics. The Finite Volume method with moving computational mesh support is used to implement an interface-tracking procedure, where each fluid phase is associated with a separate mesh which moves and deforms according to interface motion. Mathematical model governing incompressible fluid flow is solved on each moving mesh separately and coupling is accomplished by enforcing the kinematic and dynamic conditions at the interface. Surfactant adsorption/desorption at the interface is modelled using the Langmuir kinetic law, while surface tension is calculated from surfactant concentration at the interface using the nonlinear Frumkin-Langmuir equation of state. Surfactant transport along the interface is calculated using a Finite Area Method for discretisation of surface transport equation on a curved and moving unstructured surface mesh. The numerical procedure is used to simulate the effects of soluble surfactants on the motion of a free-rising air bubble in still water. The bubble of 2 mm diameter is considered, where experiments show ellipsoidal bubble shape and motion along a zig-zag and/or a helicoidal path. Calculations are performed for a clean and contaminated bubble and the results shows good agreement with available experimental data.

finite volume method; finite area method; moving mesh; interface tracking; soluble surfactants; free-rising bubble

nije evidentirano