Coupled Lagrangian and Eulerian Simulation of Bubbly Flows in Vertical Pipes: Validation with Experimental Data Using Multi- Sensor Conductivity Probes and Laser Doppler Anemometry

A set of two phase flow experiments for conditions ranging from bubbly flow to cap/slug flow have been performed under isothermal concurrent air-water flow conditions in a vertical column of 3 m height. Also the liquid properties like the surface tension have varied by adding small quantities of 1-Butanol in order to see how these changes affect to the two phase flow properties. Numerical simulations of these experiments for bubbly flow conditions were performed by coupling a Lagrangian code that tracks the 3D motion of the individual bubbles in cylindrical coordinates ) , , ( z r  inside the fluid field under the action of the following forces: buoyancy, drag, lift, wall lubrication. Also we have incorporated a 3D stochastic differential equation model to account for the random motion of the individual bubbles in the turbulent velocity field of the carrier liquid. Also we have considered the deformation that suffers the bubbles when they touch the walls of the pipe and are compressed until they rebound. The velocity and turbulence fields of the liquid phase were computed by solving the time dependent conservation equations in its Reynols Averaged Transport Equation form (RANS). The turbulent kinetic energy k, and the dissipation rate  transport equations were simultaneously solved by using the k, epsilon model in a (r,z) grid by the finite volume method using the SIMPLER algorithm. Both Lagrangian and Eulerian calculations were performed in parallel and an iterative self-consistent method was developed.