A new model for two-layer liquid-gas stratified flows in pipes with general cross sections

Fuente: arXiv
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Autori principali: Shah, Sarswati, Hernández-Dueñas, Gerardo
Natura: Preprint
Pubblicazione: 2026
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author Shah, Sarswati
Hernández-Dueñas, Gerardo
author_facet Shah, Sarswati
Hernández-Dueñas, Gerardo
contents In this work, we derive a new model for immiscible two-layer gas-liquid stratified flows in pipes with general cross sections. The bottom layer is occupied by an incompressible fluid in liquid phase with hydrodynamics based on a hydrostatic pressure, following a shallow water approximation. The top layer is occupied by a compressible gas, following an ideal gas law leading to conservation of mass, momentum and energy. The two subsystems are linked through non-conservative products, representing momentum and energy exchanges between layers. The hyperbolic properties of the resulting model are analyzed, including the derivation of entropy inequalities, and the approximations of eigenvalues of the corresponding coefficient matrix. Numerical tests are included to demonstrate the merits of the model and the numerical approximations, including well-balancedness, Riemann problems, and perturbations and convergence toward steady states at rest. Besides simulations of water and air where the density difference between layers is significant, a case where such difference is not so pronounced (like gas and liquid hydrogen) is also shown.
format Preprint
id arxiv_https___arxiv_org_abs_2602_12290
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A new model for two-layer liquid-gas stratified flows in pipes with general cross sections
Shah, Sarswati
Hernández-Dueñas, Gerardo
Computational Physics
Numerical Analysis
Analysis of PDEs
Fluid Dynamics
35L65, 76N15, 76Bxx
In this work, we derive a new model for immiscible two-layer gas-liquid stratified flows in pipes with general cross sections. The bottom layer is occupied by an incompressible fluid in liquid phase with hydrodynamics based on a hydrostatic pressure, following a shallow water approximation. The top layer is occupied by a compressible gas, following an ideal gas law leading to conservation of mass, momentum and energy. The two subsystems are linked through non-conservative products, representing momentum and energy exchanges between layers. The hyperbolic properties of the resulting model are analyzed, including the derivation of entropy inequalities, and the approximations of eigenvalues of the corresponding coefficient matrix. Numerical tests are included to demonstrate the merits of the model and the numerical approximations, including well-balancedness, Riemann problems, and perturbations and convergence toward steady states at rest. Besides simulations of water and air where the density difference between layers is significant, a case where such difference is not so pronounced (like gas and liquid hydrogen) is also shown.
title A new model for two-layer liquid-gas stratified flows in pipes with general cross sections
topic Computational Physics
Numerical Analysis
Analysis of PDEs
Fluid Dynamics
35L65, 76N15, 76Bxx
url https://arxiv.org/abs/2602.12290