Ronald Remmerswaal

Bio: Ronald Remmerswaal is an academic researcher. The author has contributed to research in topics: Two-phase flow & Volume of fluid method. The author has an hindex of 1, co-authored 4 publications receiving 134 citations.

Numerical modeling of two-phase flows using the two-fluid two-pressure approach

Abstract: The present paper is devoted to the computation of two-phase flows using the two-fluid approach. The overall model is hyperbolic and has no conservative form. No instantaneous local equilibrium between phases is assumed, which results in a two-velocity two-pressure model. Original closure laws for interfacial velocity and interfacial pressure are proposed. These closures allow to deal with discontinuous solutions such as shock waves and contact discontinuities without ambiguity with the definition of Rankine–Hugoniot jump relations. Each field of the convective system is investigated, providing maximum principle for the volume fraction and the positivity of densities and internal energies are ensured when focusing on the Riemann problem. Two-finite volume methods are presented, based on the Rusanov scheme and on an approximate Godunov scheme. Relaxation terms are taken into account using a fractional step method. Eventually, numerical tests illustrate the ability of both methods to compute two-phase flows.

Parabolic interface reconstruction for 2D volume of fluid methods

Abstract: For capillary driven flow the interface curvature is essential in the modelling of surface tension via the imposition of the Young-Laplace jump condition. We show that traditional geometric volume of fluid (VoF) methods, that are based on a piecewise linear approximation of the interface, do not lead to an interface curvature which is convergent under mesh refinement in time-dependent problems. Instead, we propose to use a piecewise parabolic approximation of the interface, resulting in a class of piecewise parabolic interface calculation (PPIC) methods. In particular, we introduce the parabolic LVIRA and MoF methods, PLVIRA and PMoF, respectively. We show that a Lagrangian remapping method is sufficiently accurate for the advection of such a parabolic interface. It is numerically demonstrated that the newly proposed PPIC methods result in an increase of reconstruction accuracy by one order, convergence of the interface curvature in time-dependent advection problems and Weber number independent convergence of a droplet translation problem, where the advection method is coupled to a two-phase Navier--Stokes solver.

Towards numerical simulation of wave impacts in an LNG tank

Abstract: During the transport of Liquefied Natural Gas (LNG) in LNG carriers sloshing can dangerously interfere with the ship motion through violent breaking-wave impacts with the container walls. The role of free surface instabilities during these impacts is not well understood [Lafeber et al., 2012]; we will study it via computer simulation. Its numerical modeling involves dealing with multi-phase flow, featuring a multitude of jumps (discontinuities) of fluid properties across the interface separating the fluids. The thin shear layers around the interface usually are numerically underresolved and result in unphysical interaction between the two fluids. Such an underresolved layer is numerically better described by a velocity field which has a (contact) discontinuity in the tangential direction. 2 Mathematical model

NEPTUNE : A new software platform for advanced nuclear thermal hydraulics

Abstract: The NEPTUNE project constitutes the thermal-hydraulic part of the long-term Electricite de France and Commissariat a l’Energie Atomique joint research and development program for the next generatio...

Analysis and approximation of a scalar conservation law with a flux function with discontinuous coefficients

Abstract: We study here a model of conservative nonlinear conservation law with a flux function with discontinuous coefficients, namely the equation ut + (k(x)u(1 - u))x = 0. It is a particular entropy condition on the line of discontinuity of the coefficient k which ensures the uniqueness of the entropy solution. This condition is discussed and justified. On the other hand, we perform a numerical analysis of the problem. Two finite volume schemes, the Godunov scheme and the VFRoe-ncv scheme, are proposed to simulate the conservation law. They are compared with two finite volume methods classically used in an industrial context. Several tests confirm the good behavior of both new schemes, especially through the discontinuity of permeability k (whereas a loss of accuracy may be detected when industrial methods are performed). Moreover, a modified MUSCL method which accounts for stationary states is introduced.

Relaxation and numerical approximation of a two-fluid two-pressure diphasic model

Abstract: This paper is concerned with the numerical approximation of the solutions of a two-fluid two-pressure model used in the modelling of two-phase flows. We present a relaxation strategy for easily dealing with both the nonlinearities associated with the pressure laws and the nonconservative terms that are inherently present in the set of convective equations and that couple the two phases. In particular, the proposed approximate Riemann solver is given by explicit formulas, preserves the natural phase space, and exactly captures the coupling waves between the two phases. Numerical evidences are given to corroborate the validity of our approach.