Advection-modulated gaseous diffusion through an orifice

Fuente: arXiv
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Auteurs principaux: Sanz, Mario Sánchez, Sánchez, Antonio L.
Format: Preprint
Publié: 2026
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author Sanz, Mario Sánchez
Sánchez, Antonio L.
author_facet Sanz, Mario Sánchez
Sánchez, Antonio L.
contents We examine flow and transport through an orifice in a flat wall separating semi-infinite atmospheres of two dissimilar gases. The analysis assumes steady conditions and order-unity values of the Schmidt number Sc and Péclet number Pe, such that advection and diffusion contribute comparably to mass and momentum transport. Mixing between the two gases induces order-unity variations in viscosity and density, resulting in coupled concentration and velocity fields. The solution yields the mass transfer rates of both gases, expressed in terms of an appropriately defined Sherwood number, as well as the overpressure required to sustain the flow, all as functions of Sc and Pe. An explicit analytical solution is obtained in the limit of small Pe, while numerical integration is used to describe flows with Pe = O(1). The mixing of hydrogen and air is used as an illustrative example that serves to highlight the influence of large gas-molecular-weight differences on the flow structure and associated mixing rate, with additional selected results given for the case of hydrogen and water vapor.
format Preprint
id arxiv_https___arxiv_org_abs_2602_20914
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Advection-modulated gaseous diffusion through an orifice
Sanz, Mario Sánchez
Sánchez, Antonio L.
Fluid Dynamics
We examine flow and transport through an orifice in a flat wall separating semi-infinite atmospheres of two dissimilar gases. The analysis assumes steady conditions and order-unity values of the Schmidt number Sc and Péclet number Pe, such that advection and diffusion contribute comparably to mass and momentum transport. Mixing between the two gases induces order-unity variations in viscosity and density, resulting in coupled concentration and velocity fields. The solution yields the mass transfer rates of both gases, expressed in terms of an appropriately defined Sherwood number, as well as the overpressure required to sustain the flow, all as functions of Sc and Pe. An explicit analytical solution is obtained in the limit of small Pe, while numerical integration is used to describe flows with Pe = O(1). The mixing of hydrogen and air is used as an illustrative example that serves to highlight the influence of large gas-molecular-weight differences on the flow structure and associated mixing rate, with additional selected results given for the case of hydrogen and water vapor.
title Advection-modulated gaseous diffusion through an orifice
topic Fluid Dynamics
url https://arxiv.org/abs/2602.20914