JNST : Vol. 41 (2004) , No. 3 p.331-338

Balance of Liquid-phase Turbulence Kinetic Energy Equation for Bubble-train Flow

Milica ILIC¹⁾, Martin WÖRNER¹⁾ and Dan Gabriel CACUCI¹⁾

1) Forschungszentrum Karlsruhe, Institut für Reaktorsicherheit

(Received July 18, 2003)

In this paper the investigation of bubble-induced turbulence using direct numerical simulation (DNS) of bubbly two-phase flow is reported. DNS computations are performed for a bubble-driven liquid motion induced by a regular train of ellipsoidal bubbles rising through an initially stagnant liquid within a plane vertical channel. DNS data are used to evaluate balance terms in the balance equation for the liquid phase turbulence kinetic energy. The evaluation comprises single-phase-like terms (diffusion, dissipation and production) as well as the interfacial term. Special emphasis is placed on the procedure for evaluation of interfacial quantities. Quantitative analysis of the balance equation for the liquid phase turbulence kinetic energy shows the importance of the interfacial term which is the only source term. The DNS results are further used to validate closure assumptions employed in modelling of the liquid phase turbulence kinetic energy transport in gas–liquid bubbly flows. In this context, the performance of respective closure relations in the transport equation for liquid turbulence kinetic energy within the two-phase k–ε and the two-phase k–l model is evaluated.

bubble-induced turbulence turbulence kinetic energy direct numerical simulation bubble-train flow turbulence modelling