RT Journal Article
ID 4212285a2774c7f6
A1 Fleau, SolĂ¨ne
A1 Mimouni, Stephane
A1 Merigoux, Nicolas
A1 Vincent, Stephane
T1 VALIDATION OF A MULTIFIELD APPROACH FOR THE SIMULATIONS OF TWO-PHASE FLOWS
JF Computational Thermal Sciences: An International Journal
JO CTS
YR 2015
FD 2016-06-27
VO 7
IS 5-6
SP 441
OP 457
K1 two-phase flows
K1 multifield approach
K1 drag force
K1 interface sharpening
K1 capillary effects
K1 large bubble test cases
K1 free surface
AB Safety issues in nuclear power plant involve complex bubbly flows. To predict the behavior of these flows, the two-fluid approach is often used. Nevertheless, this model induces a numerical diffusion of interfaces, which results in a poor accuracy in the calculation of the local parameters. Therefore, to simulate large interfaces such as slugs or free surfaces, interface tracking methods have been developed using the single-fluid model. In this paper, the two approaches have been coupled in the CMFD code NEPTUNE_CFD to simulate adiabatic separated flows. The averaged momentum balance equations are solved for each field and are followed by an artificial compression step, which fixes the interface thickness and ensures mass conservation. Moreover, since the two-fluid model defines a velocity per field in the whole computational domain, a drag force is used to couple the velocity of each field at the interface. This article proposes also a new formulation for this force, to take into account the physical properties of the flow. To validate this approach, an analytical test case with a static bubble has been simulated with a mesh refinement test. Then, the simulations of a rising bubble, an oscillating bubble, and the Kelvin-Helmholtz instability have been performed to highlight the effect of the modification of the drag force. Finally, model comparisons are proposed with the Kelvin-Helmholtz and the Rayleigh-Taylor instabilities.
PB Begell House
LK http://dl.begellhouse.com/journals/648192910890cd0e,4860a26f63ba7840,4212285a2774c7f6.html