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ballistic and collisional flow contributions to anti-fourier heat transfer in rarefied cavity flow

by:Mingfa Tech     2020-01-12
This article against
Fourier heat transfer phenomenon in rare gases confined to the lid
Since the cavity directly simulates Monte Carlo using a new flow decomposition technology (DSMC)
Methods proposed by Stefanov and co-workers.
Considering the constant temperature cavity with different degrees of sparse flow from the near continuum to the intermediate transition zone to study the cold-to-
Heat transfer from the perspective of ballistic/collision flow decomposition. A new cold-to-
A heat transfer indicator in the form of scalar product with standardized heat flow vectors and standardized temperature gradient vectors has been introduced for the overall, bullet and collision sections of these vectors.
Using new indicators, the contribution of the elastic and collision flow parts to temperature and heat flux components was studied, with special emphasis on cold-to-
Heat transmission phenomenon.
We have proved that both the bullet and the collision flow part contribute to the cold-to-
Heat transfer.
However, the study found that the elastic and collision parts of heat transfer are considered separately, and they become more and more hot when related to the corresponding elastic and collision temperature fields. to-
All levels of flow are scarce. Thus, cold-to-
Heat transfer is the result of subtle interactions between the ballistic part and the collision part in the state of sliding and transition Knudsen.
Recently,Fourier (
Also known as coldto-hot or counter-gradient)
Based on the molecular simulation of gas flow directly simulated Monte Carlo, the heat transfer phenomenon in sparse gas flow has been reported (DSMC)method. John .
The effects of expansion cooling and viscous heat dissipation on the heat transfer mechanism of the lid were studied.
Drive cavity under non-equilibrium flow conditions.
They observed a reaction.
Gradient heat transfer in sliding
Flow State simulated using DSMC, which is unpredictable by classic NaviStokes-Fourier (NSF)equations. Mohammadzadeh .
Studied Micro
And details of the flow of nano-space.
They proved the existence of unconventional cold. to-
The heat transfer is strongly dependent on the Reynolds number, and the heat transfer disappears for large Reynolds number/Mach number flows.
Using molecular entropy analysis, they found coldto-
The heat transfer in the cavity conforms to the second law of thermodynamics and is carried out in the direction of increasing entropy. Rana .
It is shown that, contrary to the NSF equation, 13 moments of DSMC and regularization (R13)
Method can predict the inverse
Fourier heat transfer.
The R13 moment method is described by the macroscopic transport equations of three levels in Chapman-Middle Knudsen number
Enskog sense of approximation.
This approach combines Grad-
Style square and Burnett-
The inadequacies of them are omitted.
They suggest that the reverse heat flow may be related to the shear stress gradient in the region, especially near the wall.
Julu and Dadzie studied micro-
Cavity heat transfer problem using new continuum model Bi-
The velocity model provides modifications to the standard NSF equation that simulates sparse gas flow.
They showed the cold. to-
Heat transfer can be simulated by using a new molecular corrected NSF equation
Horizontal diffusion flux associated with the concentration of gas molecules. The counter-
Gradient heat flow under pressure
John has also observed the flow of the drive plane phoneuille. and Akhlaghi . .
According to observation, coldto-
In the case of a cooling wall, heat transfer occurs in the terminal part of the channel.
At the same time, on a similar wall
Under the condition of inflow temperature, coldto-
Under sufficiently high purification conditions, heat transfer exists along the center line of the channel. Balaj .
The shear work pair caused by speed sliding is studied.
Equilibrium heat transfer under pressure
Under the specified wall heat flow conditions, the driving gas flows through the micro-channel.
They analyzed the opposite.
Gradient heat flow phenomena appearing under cooling conditions show that viscous dissipation and shear work play an important role in the heat flow pattern under sparse conditions. Balaj .
Three different heat flow patterns are classified. e. , complete hot-to-
Cold, whole reverse
Fourier and local inverse
Fourier heat transfer under pressure
The gas flows through the micro-channel under constant wall heat flow conditions.
The competition between the contribution of the temperature gradient and the pressure gradient is observed (shear stress)
And the viscous sliding heating strongly affects the heat flow pattern in the micro and nano channels.
Recently, Rui.
Cold detectedto-
Thermal transfer phenomenon in nano-materials
Triangular cavity of isosceles.
They showed
The Fourier heat transfer is due to the terms of competition and the non-linear relationship of the Fourier heat flow of the shear stress gradient component
Balance system. A cold-to-
In the sliding state, heat transfer is observed near the moving lid, which is due to the sharp bending of the velocity distribution of the cavity corners, amplification of the velocity gradient contribution in the law of heat flow composition (
Second order in Knudsen number)
Compared with the first order Fourier term.
With the further increase in the number of knusen during the transition period, they indicate the cold areasto-
Heat transfer takes up almost the entire area, while most of the hotlines point to the inclined surface of the triangle.
In the present work, weto-
Heat Transfer in lid
Sparse cavity flow driven by the decomposition method first proposed recently.
The elastic and collision parts of DSMC solution in the cavity were calculated respectively, and the contribution of each part to the overall heat transfer mode was analyzed.
Similar methods were used before to explain themselves.
Diffusion and sparse gas short tube propulsion efficiency in long capillary tubes.
These forms of decomposition (
Bullet and collision parts)
The macroscopic flow characteristic is introduced.
By using a new cold indicator to consider the elastic and collision parts of the heat flow and temperatureto-
The heat transfer reveals the cold-to-
In the cavity geometry, heat transfer in the flow of rare gases.
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