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The optimal control of a globally unstable two-dimensional separated boundary layer over a bump is considered using augmented Lagrangian optimization procedures. The present strategy allows of controlling the flow from a fully developed…

Fluid Dynamics · Physics 2018-03-14 Pierre-Yves Passaggia , Uwe Ehrenstein

The collapse of a gas or vapour bubble near a non-porous boundary is directed at the boundary due to the asymmetry induced by the nearby boundary. High surface pressure and shear stress from this collapse can damage, or clean, the surface.…

Fluid Dynamics · Physics 2023-05-10 Elijah D. Andrews , David Fernández Rivas , Ivo R. Peters

The flow driven by a rapidly expanding and collapsing cavitation bubble in a narrow cylindrical gap is studied with the volume of fluid method. The simulations reveal a developing plug flow during the early expansion followed by flow…

Fluid Dynamics · Physics 2017-02-01 Milad Mohammadzadeh , Fenfang Li , Claus-Dieter Ohl

A new type of two phase coexistence in a vibrated granular material is reported, in the limit where energy transfer between the particles and the bottom wall occurs due to discrete collisions. A horizontally homogeneous bed develops…

Statistical Mechanics · Physics 2007-05-23 P Sunthar , V Kumaran

This brief note addresses the free boundary problem arising from the steady two-dimensional seepage flow through a rectangular dam. The flow problem consists in finding the free boundary location, and the velocity and pressure fields. The…

Fluid Dynamics · Physics 2015-07-21 Carmine Di Nucci

Pore-resolved direct numerical simulations of turbulent open channel flow are performed comparing the structure and dynamics of turbulence over impermeable rough and smooth walls to a porous sediment bed at permeability Reynolds number…

Fluid Dynamics · Physics 2022-05-02 Shashank K. Karra , Sourabh V. Apte , Xiaoliang He , Timothy D. Scheibe

The interaction between the flow above and below a permeable wall is a central topic in the study of porous media. While previous investigations have provided compelling evidence of the strong coupling between the two regions, few studies…

Fluid Dynamics · Physics 2021-07-07 Wenkang Wang , Xu Chu , Adrián Lozano-Durán , Rainer Helmig , Bernhard Weigand

We use existing 3D Discrete Element simulations of simple shear flows of spheres to evaluate the radial distribution function at contact that enables kinetic theory to correctly predict the pressure and the shear stress, for different…

Soft Condensed Matter · Physics 2014-06-03 Dalila Vescovi , Diego Berzi , Patrick Richard , Nicolas Brodu

For dry foams, the transport of gas from small high-pressure bubbles to large low-pressure bubbles is dominated by diffusion across the thin soap films separating neighboring bubbles. For wetter foams, the film areas become smaller as the…

Soft Condensed Matter · Physics 2017-10-04 C. D. Schimming , D. J. Durian

Discrete element method simulations of confined bidisperse granular shear flows elucidate the balance between diffusion and segregation that can lead to either mixed or segregated states, depending on confining pressure. Results indicate…

Soft Condensed Matter · Physics 2018-09-24 Alexander M. Fry , Paul B. Umbanhowar , Julio M. Ottino , Richard M. Lueptow

In this paper we study a model of an interface between two fluids in a porous medium. For this model we prove several local and global well-posedness results and study some of its qualitative properties. We also provide numerics.

Analysis of PDEs · Mathematics 2015-06-22 Rafael Granero-Belinchón , Gustavo Navarro , Alejandro Ortega

This paper reports turbulent boundary layer measurements made over open-cell reticulated foams with varying pore size and thickness, but constant porosity ($\epsilon \approx 0.97$). The foams were flush-mounted into a cutout on a flat…

Fluid Dynamics · Physics 2018-03-14 Christoph Efstathiou , Mitul Luhar

The complex interaction between turbulence and the free surface in boundary layer shear flow created by a vertical surface-piercing wall is considered. A laboratory-scale device was built that utilizes a surface-piercing stainless steel…

Fluid Dynamics · Physics 2017-03-29 Nathan Washuta , Naeem Masnadi , James H. Duncan

We study average flow properties in porous media using a two-dimensional network simulator. It models the dynamics of two-phase immiscible bulk flow where film flow can be neglected. The boundary conditions are biperiodic which provide a…

Soft Condensed Matter · Physics 2007-05-23 Henning Arendt Knudsen , Alex Hansen

Turbulent boundary layers exhibit a universal structure which nevertheless is rather complex, being composed of a viscous sub-layer, a buffer zone, and a turbulent log-law region. In this letter we present a simple analytic model of…

Chaotic Dynamics · Physics 2007-05-23 Victor S. L'vov , Itamar Procaccia , Oleksii Rudenko

We consider a shear layer of a kind not previously studied to our knowledge. Contrary to the classical free shear layer, the width of the shear zone does not vary in the streamwise direction but rather exhibits a lateral variation. Based on…

Fluid Dynamics · Physics 2012-09-05 Vagesh D. Narasimhamurthy , Simen Å. Ellingsen , Helge I. Andersson

Characteristics of Oscillating Flow in a Straight Tube with varying thickness of porous layer at the wall is studied. Results for two different porous layer is discussed and compared in terms of Velocity Profile, phase differences and…

Fluid Dynamics · Physics 2021-04-28 Pawan Kumar Pandey , Malay Kumar Das

Boundary layer flow over a realistic porous wall might contain both the effects of wall-permeability and wall-roughness. These two effects are typically examined in the context of a rough-wall flow, i.e., by defining a ``roughness'' length…

Fluid Dynamics · Physics 2023-07-26 D. D. Wangsawijaya , P. Jaiswal , B. Ganapathisubramani

In the present study, we conduct direct numerical simulations to investigate the near-wall dynamics of compressible turbulent boundary layers at the free-stream Mach number of 6 laden with heavy particles. By inspecting the instantaneous…

Fluid Dynamics · Physics 2025-05-14 Ming Yu , Lihao Zhao , Yibin Du , Xianxu Yuan , Chunxiao Xu

Turbulent flows over porous lattices consisting of rectangular cuboid pores are investigated using scale-resolving direct numerical simulations. Beyond a certain threshold which is primarily determined by the wall-normal Darcy permeability,…

Fluid Dynamics · Physics 2024-04-17 Seyed Morteza Habibi Khorasani , Mitul Luhar , Shervin Bagheri