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Hele-Shaw flow

About: Hele-Shaw flow is a research topic. Over the lifetime, 5451 publications have been published within this topic receiving 151320 citations.


Papers
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Journal ArticleDOI
TL;DR: A convenient detector is introduced for coherent flow structures, the fraction of time the structures appear in the flow is calculated, and a Markov model for the transition between the structures is presented.
Abstract: Numerical and experimental studies of transitional pipe flow have shown the prevalence of coherent flow structures that are dominated by downstream vortices. They attract special attention because they contribute predominantly to the increase of the Reynolds stresses in turbulent flow. In the present study we introduce a convenient detector for these coherent states, calculate the fraction of time the structures appear in the flow, and present a Markov model for the transition between the structures. The fraction of states that show vortical structures exceeds 24% for a Reynolds number of about $\mathrm{Re}=2200$, and it decreases to about 20% for $\mathrm{Re}=2500$. The Markov model for the transition between these states is in good agreement with the observed fraction of states, and in reasonable agreement with the prediction for their persistence. It provides insight into dominant qualitative changes of the flow when increasing the Reynolds number.

93 citations

Journal ArticleDOI
H. Pascal1
TL;DR: In this paper, the threshold gradient effect in nonsteady flow through a porous media is investigated and its role on the pressure and flow rate distributions in a flow system is evaluated.
Abstract: In this paper the threshold gradient effect in the nonsteady flow through a porous media is investigated and its role on the pressure and flow rate distributions in a flow system is evaluated. The system considered in this investigation is a linear oil reservoir. Two situations of practical interest, i.e. reservoir depleted at a constant pressure and at a constant flow rate, are considered. The solutions in a closed form for this flow system are obtained. A comparison between the pressure distributions obtained analytically, numerically and by the integral method is also presented. In order to illustrate the effect that threshold gradient would have on the flow behavior, several numerical examples are given. The results derived from this investigation show that the flow behavior in the presence of a threshold gradient depends strongly on two dimensionless parameters. These parameters are directly related to the threshold gradient, the physical properties of the porous medium and the flow parameters at the outface flow.

92 citations

Journal ArticleDOI
TL;DR: In this article, a computational and experimental study has been performed for the investigation of fully developed rarefied gas flows through channels of circular, orthogonal, triangular, and trapezoidal cross sections.
Abstract: A computational and experimental study has been performed for the investigation of fully developed rarefied gas flows through channels of circular, orthogonal, triangular, and trapezoidal cross sections. The theoretical-computational approach is based on the solution of the Bhatnagar-Gross-Krook kinetic equation subject to Maxwell diffuse-specular boundary conditions by the discrete velocity method. The experimental work has been performed at the vacuum facility “TRANSFLOW,” at Forschungszentrum Karlsruhe and it is based on measuring, for assigned flow rates, the corresponding pressure differences. The computed and measured mass flow rates and conductance are in all cases in very good agreement. In addition, in order to obtain some insight in the flow characteristics, the reference Knudsen, Reynolds, and Mach numbers characterizing the flow at each experimental run have been estimated. Also, the pressure distribution along the channel for several typical cases is presented. Both computational and experimental results cover the whole range of the Knudsen number.

92 citations

Journal ArticleDOI
TL;DR: In this article, the use of proper unwind schemes is recommended for vortical flow simulations at a high Reynolds number, and verification of computed result is especially important for VF simulations.
Abstract: One of the high-resolution upwind schemes called "MUSCL with Roe's average" is applied to vortical flow simulations. Two examples are considered. One is the leading-edge, separation-vortex flow over a strake-delta wing. The other is a high angle-of-attack supersonic flow over a space-plane-like configuration. The comparison with the central-difference solutions indicates that the present upwind scheme is less dissipative and thus has better resolution for the vortical flows. Thus, it is concluded that the use of proper unwind schemes is recommended for vortical flow simulations at a high Reynolds number, and verification of computed result is especially important for vortical-flow simulations.

92 citations

Journal ArticleDOI
TL;DR: In this paper, the authors measured the streamwise component of the turbulence intensity in a fully developed pipe flow at Reynolds numbers up to 145 000 and showed that the magnitude of the near-wall peak is invariant with Reynolds number in location and magnitude.
Abstract: New measurements of the streamwise component of the turbulence intensity in a fully developed pipe flow at Reynolds numbers up to 145 000 indicate that the magnitude of the near-wall peak is invariant with Reynolds number in location and magnitude. The results agree with previous pipe flow data that have sufficient spatial resolution to avoid spatial filtering effects, but stand in contrast to similar results obtained in boundary layers, where the magnitude of the peak displays a prominent Reynolds number dependence, although its position is fixed at the same location as in pipe flow. This indicates that the interaction between the inner and outer regions is different in pipe flows and boundary layers.

91 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202339
202282
202120
202013
20199
201829