Dr. Dirk Lucas

Head Computational Fluid Dynamics
Phone: +49 351 260 2047

Baseline-Modell für polydisperse Blasenströmungen – iMUSIG

Closure of the two-fluid model for bubbly flow is a very challenging problem due to complex relations between interfacial transfer, turbulence and bubble size. One active research topic in the department of Computational Fluid Dynamics is the validation and development of the baseline model for poly-disperse bubbly flows.

HZDR baseline model strategy

To consolidate multiphase CFD in frame of the Euler-Euler approach well defined baseline models are established and improved step by step. The same model can be used for different applications.
Foto: HZDR Baseline-Modell für polydisperse Blasenströmungen - link ©Copyright: Torsten Berger

HZDR baseline model for poly-disperse bubbly flows

Information on how to setup a simulation of bubbly flows and the exact definition of the closure models in the present ­version of the baseline model for poly-dispersing bubbly flows.
Foto: iMusig - link ©Copyright: Torsten Berger

Inhomogeneous MUSIG (iMUSIG) approach

The closure models may depend sensitively on bubble, drop or particle size. This may lead e.g. to a se­paration of small and large bubbles. The iMUSIG approach allows the sub-division of the disperse phase in sub-phases and the combination with a population balance.
Foto: Bubble-induced turbulence - link ©Copyright: Torsten Berger

Turbulence modelling in bubbly flows

A new model to consi­der the bubble induced turbulence (BIT) was recently derived basing on data from direct numerical simulations (DNS). Basing on the shear stress turbulence (SST) model additional source terms are proposed for BIT.
Foto: Bubble coalescence and breakup - link ©Copyright: Torsten Berger

Bubble coalescence and breakup

The models for bubble coalescence and breakup consi­der the different mechanisms which may lead to a merging of bubbles or their fragmentation.
Foto: Euler-Euler-modelling of reactive flow in bubble columns - link ©Copyright: Torsten Berger

Euler-Euler-modeling of reactive flow in bubble columns

In the frame of a project within the DFG priority program 1740 “Influence of Local Transport Processes on Chemical Reactions in Bubble Flows” closure models for chemical reaction as well as the associated mass transport are included in the Euler-Euler description of bubbly flows.
Foto: Strömungen mit Verdampfung und Kondensation - link ©Copyright: Torsten Berger

Evaporating and condensing flows

For many applications evaporation and condensation processes are important. Models are developed for wall boiling including the consideration of critical heat flux (CHF), for boiling flows caused by pressure decrease and for condensing flows.
Foto: BubFind ©Copyright: Dr. Hendrik Hessenkemper

Experimental methods for optical measurements in bubbly flows

To obtain high resolution flow data of dispersed bubble flows, we use optical measurements and develop suitable processing tools. This involves PIV-like methods and Lagrangian Particle Tracking for the liquid phase and deep learning models for detecting and tracking individual bubbles under strong occlusion.