Rarefied flow and heat transfer characteristics of rectangular cavities with heated concave surface

Alkhalidi, Ammar; Kiwan, Suhil; Al‐Kouz, Wael; Owhaib, Wahib; Alshare, Aiman

doi:10.1177/1687814019860988

Cited by 10 publications

(4 citation statements)

References 23 publications

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“…Therefore, larger Darcy numbers tend to have greater flow circulation than lower Darcy numbers. Previously, Alkhalidi et al 40 indicated that the concave shape of the rigid wall reduces the flow circulation.…”

Section: Resultsmentioning

confidence: 99%

Unsteady free convection in a composite enclosure having flexible wall

Alhashash

Saleh

2023

Advances in Mechanical Engineering

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Transient free convection in a composite enclosure having a cold flexible plate and a hot rigid plate is simulated numerically. It is assumed that the flexible plate is hyper-elastic. A porous layer with various sizes and permeabilities is attached to the rigid plate. The enclosure is filled with water. Fluid flow in the fluid domain was governed by the Navier–Stokes equations, and the flow within a saturated porous layer was governed by the Brinkman-Forchheimer extended Darcy model. The unsteady continuity, momentum, and energy equations are solved using the Arbitrary-Lagrangian-Eulerian (ALE) approach based on the fluid-structure interaction (FSI). It is found that the development of convective flow goes through initial, transitional, and stationary states. Each state interval is shifted by varying the Darcy number and Rayleigh number. In the transitional state, the deformation of the flexible parts reaches its maximum bending. The profile of the flexible plate at steady state is in a sinusoidal shape for the non-Darcy regime, while it is in an asymmetric parabolic shape for the Darcy regime. The steady state is reached for [Formula: see text], [Formula: see text], and [Formula: see text] before [Formula: see text].

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Section: Resultsmentioning

confidence: 99%

Unsteady free convection in a composite enclosure having flexible wall

Alhashash

Saleh

2023

Advances in Mechanical Engineering

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“…41 No slip velocity boundary condition is imposed for the air at the surfaces which is considered to be zero in the case of simulation of the normal atmospheric model. Whereas in the case of air vacuum in the channel, the temperature jumps and slip flow boundary conditions are considered and adjusted by Knudsen number according to the following equations 42,43 :…”

Section: Mathematical Modeling and Numerical Solutionmentioning

confidence: 99%

Performance study of an isolated small scale Trombe wall with partially evacuated air gap

Ali,

Mawlood,

Jalal

2024

Advances in Mechanical Engineering

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The Trombe wall is a passive solar heating system that aims to mitigate heating load. However, its efficiency is impeded by significant heat loss through the glazing. To address this issue, a novel technique has been developed that involves partial evacuation of the space between the storage wall and the glazing. This approach, which has already found successful application in double-paned windows and solar collectors, is examined in this study to evaluate its impact on the performance of an isolated Trombe wall. An effectiveness criterion based on the ability of a system to preserve its stored thermal energy is defined and used for assessing the performance of a vacuumed system relative to a non-vacuumed one. An experimental test cell, composed of a solid concrete wall serving as a thermal storage and a glazing separated from the wall by an air gap, facing south is constructed in Kirkuk, Iraq. The wall is insulated at all its sides except the side facing the glass. The gap has been sealed meticulously to maintain a vacuum. Due to unrepeatability of the testing conditions experimentally, a numerical method and a computer code is also developed for simulation of the system. Measurement results obtained from the test cell under normal atmospheric pressure and a gage pressure of −0.3 bar of the air gap are used to validate the numerical method. The code is then used to simulate the performance of the system under the same ambient conditions but at different vacuum pressures of the air gap. Results obtained from the numerical tests show that partial evacuation of the air gap can be an efficient way to enhance the performance of the Trombe wall and the absolute pressure of 0.1 bar results in the most significant increase in the effectiveness of the studied model.

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“…Understanding these influences is crucial for accurately modeling and predicting flow behaviour, especially in microscale applications, low-pressure environments, or scenarios where rarefied gas effects are prominent. Specialized numerical methods and experimental techniques are often required to capture these effects accurately [9,11,18,19,20]. In our previous studies [10,12,13,14], we considered rarefied monatomic gas between two coaxial unconfined cylinders (one dimensional, axisymmetric problem) by using a statistical method -Direct Simulation Monte Carlo (DSMC) and the Navier-Stokes-Fourier equations numerical solving.…”

Section: Introductionmentioning

confidence: 99%

Oscillating flow of rarefied viscous gas between cylinders of finite length. Numerical study

Gospodinov,

Dankov,

Mironova

2023

J. Phys.: Conf. Ser.

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The rarefied viscous gas flow between a stationary inner and an oscillating outer cylinder is studied in this paper. It is a continuation of our previous publications where we study the flow between the infinite length cylinders while here is considered the case of finite length cylinders bounded by two planes with periodic boundary conditions in the cross sections at the ends of the cylinders. So, on the one hand, this changes the flow character creating conditions for periodic self-organization along the axis of symmetry and on the other hand, the current model is reduced to a flow in a limited volume. A continuum model based on Navier-Stokes-Fourier equations for compressible fluid with first order slip boundary conditions on the cylinders wall and statistical model Direct Simulation Monte Carlo (DSMC) method are used to model the flow. The presented numerical results were obtained after reaching sustained oscillations. Considering the model with cylinders of finite length allows to extend its capabilities and obtain a better fit to real conditions.

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Rarefied flow and heat transfer characteristics of rectangular cavities with heated concave surface

Cited by 10 publications

References 23 publications

Unsteady free convection in a composite enclosure having flexible wall

Unsteady free convection in a composite enclosure having flexible wall

Performance study of an isolated small scale Trombe wall with partially evacuated air gap

Oscillating flow of rarefied viscous gas between cylinders of finite length. Numerical study

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