A Numerical Study of Atmospheric Perturbations Induced by Heat From a Wildland Fire: Sensitivity to Vertical Canopy Structure and Heat Source Strength

In this study, a 3D numerical study of free ventilated room equipped with a discrete heat source was performed using the Finite Volume Method (FVM). To ensure good ventilation, two parallel openings were created in the room. A suction opening was located at the bottom of the left wall and another opening was located at the top of the opposite wall; the heat source was placed at various positions in order to compare the heating efficiency. The effects of Rayleigh number (103 ≤ Ra ≤ 106) for six heater positions was studied. The results focus on the impact of these parameters on the particle trajectories, temperature fields and on the heat transfer inside the room. It was found that the position of the heater has a dramatic effect on the behavior and topography of the flow in the room. When the heat source was placed on the wall with the suction opening, two antagonistic behaviors were recorded: an improvement in heat transfer of about 31.6%, compared to the other positions, and a low Rayleigh number against 22% attenuation for high Ra values was noted.

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Numerical Investigation of Mixed Convection and Entropy Generation in a Wavy-Walled Cavity Filled with Nanofluid and Involving a Rotating Cylinder

Entropy ◽

10.3390/e20090664 ◽

2018 ◽

Vol 20 (9) ◽

pp. 664 ◽

Cited By ~ 25

Author(s):

Ammar Alsabery ◽

Muneer Ismael ◽

Ali Chamkha ◽

Ishak Hashim

Keyword(s):

Heat Exchange ◽

Rayleigh Number ◽

Heat Source ◽

Mixed Convection ◽

Volume Fraction ◽

Numerical Study ◽

Rotational Velocity ◽

Geometrical Parameters ◽

Galerkin Finite Element ◽

Vertical Walls

This numerical study considers the mixed convection and the inherent entropy generated in Al 2 O 3 –water nanofluid filling a cavity containing a rotating conductive cylinder. The vertical walls of the cavity are wavy and are cooled isothermally. The horizontal walls are thermally insulated, except for a heat source segment located at the bottom wall. The dimensionless governing equations subject to the selected boundary conditions are solved numerically using the Galerkin finite-element method. The study is accomplished by inspecting different ranges of the physical and geometrical parameters, namely, the Rayleigh number ( 10 3 ≤ R a ≤ 10 6 ), angular rotational velocity ( 0 ≤ Ω ≤ 750 ), number of undulations ( 0 ≤ N ≤ 4 ), volume fraction of Al 2 O 3 nanoparticles ( 0 ≤ ϕ ≤ 0.04 ), and the length of the heat source ( 0.2 ≤ H ≤ 0.8 ) . The results show that the rotation of the cylinder boosts the rate of heat exchange when the Rayleigh number is less than 5 × 10 5 . The number of undulations affects the average Nusselt number for a still cylinder. The rate of heat exchange increases with the volume fraction of the Al 2 O 3 nanoparticles and the length of the heater segment.

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Numerical Study on the Electrical Performance Improvement of a Thermoelectric Generator by Changing the Parameters of Multiple Cycle Pulsed Heat Source

SSRN Electronic Journal ◽

10.2139/ssrn.3944460 ◽

2021 ◽

Author(s):

Li Kong ◽

Jia Yu ◽

Qingshan Zhu ◽

Hongji Zhu ◽

Qing Yan

Keyword(s):

Heat Source ◽

Performance Improvement ◽

Thermoelectric Generator ◽

Numerical Study ◽

Electrical Performance ◽

Multiple Cycle

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Numerical Study of a Small Droplet Movement in a Microchannel under Heat Source

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.894.104 ◽

2019 ◽

Vol 894 ◽

pp. 104-111

Author(s):

Thanh Long Le ◽

Jyh Chen Chen ◽

Huy Bich Nguyen

Keyword(s):

Contact Angle ◽

Heat Source ◽

Water Droplet ◽

Stokes Equations ◽

Numerical Study ◽

Dynamic Contact Angle ◽

Dynamic Contact ◽

Initial Position ◽

Immiscible Fluids ◽

Two Phase

In this study, the numerical computation is used to investigate the transient movement of a water droplet in a microchannel. For tracking the evolution of the free interface between two immiscible fluids, we employed the finite element method with the two-phase level set technique to solve the Navier-Stokes equations coupled with the energy equation. Both the upper wall and the bottom wall of the microchannel are set to be an ambient temperature. 40mW heat source is placed at the distance of 1 mm from the initial position of a water droplet. When the heat source is turned on, a pair of asymmetric thermocapillary convection vortices is formed inside the droplet and the thermocapillary on the receding side is smaller than that on the advancing side. The temperature gradient inside the droplet increases quickly at the initial times and then decreases versus time. Therefore, the actuation velocity of the water droplet first increases significantly, and then decreases continuously. The dynamic contact angle is strongly affected by the oil flow motion and the net thermocapillary momentum inside the droplet. The advancing contact angle is always larger than the receding contact angle during actuation process.

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