Normal-Velocity Relaxation and Higher Order Algebraic Heat Flux Models Applicable to an Axisymmetric Impinging Jet

2012 ◽  
Vol 33 (4) ◽  
pp. 556-564 ◽  
Author(s):  
Farzad Bazdidi-Tehrani ◽  
Alireza Imanifar ◽  
Siavash Khajehhasani ◽  
Mehran Rajabi-Zargarabadi
Keyword(s):  
Heat Flux ◽  
Impinging Jet ◽  
Higher Order ◽  
Normal Velocity ◽  
Order Algebraic

scholarly journals Dynamics of Extreme Stratospheric Negative Heat Flux Events in an Idealized Model

2018 ◽  
Vol 75 (10) ◽  
pp. 3521-3540 ◽  
Author(s):  
Etienne Dunn-Sigouin ◽  
Tiffany Shaw
Keyword(s):  
Heat Flux ◽  
Wave Propagation ◽  
Recent Work ◽  
Wave Interaction ◽  
Higher Order ◽  
Negative Events ◽  
Flow Mechanism ◽  
Mean Flow ◽  
Idealized Model

Recent work has shown that extreme stratospheric wave-1 negative heat flux events couple with the troposphere via an anomalous wave-1 signal. Here, a dry dynamical core model is used to investigate the dynamical mechanisms underlying the events. Ensemble spectral nudging experiments are used to isolate the role of specific dynamical components: 1) the wave-1 precursor, 2) the stratospheric zonal-mean flow, and 3) the higher-order wavenumbers. The negative events are partially reproduced when nudging the wave-1 precursor and the zonal-mean flow whereas they are not reproduced when nudging either separately. Nudging the wave-1 precursor and the higher-order wavenumbers reproduces the events, including the evolution of the stratospheric zonal-mean flow. Mechanism denial experiments, whereby one component is fixed to the climatology and others are nudged to the event evolution, suggest higher-order wavenumbers play a role by modifying the zonal-mean flow and through stratospheric wave–wave interaction. Nudging all tropospheric wave precursors (wave-1 and higher-order wavenumbers) confirms they are the source of the stratospheric waves. Nudging all stratospheric waves reproduces the tropospheric wave-1 signal. Taken together, the experiments suggest the events are consistent with downward wave propagation from the stratosphere to the troposphere and highlight the key role of higher-order wavenumbers.

Equivalence Between Higher-Order Stress Power and Heat Flux in Energy Equation Based on Lattice Dynamics

1999 ◽  
Vol 121 (2) ◽  
pp. 240-246 ◽  
Author(s):  
Y. Yasui ◽  
K. Shizawa ◽  
K. Takahashi
Keyword(s):  
Heat Flux ◽  
Lattice Dynamics ◽  
Energy Equation ◽  
Solid Mechanics ◽  
Higher Order ◽  
First Law Of Thermodynamics ◽  
Internal Forces ◽  
Order Stress ◽  
As Stress

The essence of macroscopic quantities in solid mechanics can be grasped by expressing these quantities in terms of kinematic and mechanical quantities of atoms. In this paper, a method is proposed for obtaining the microscopic definitions of internal forces of continua such as stress, higher-order stresses and heat flux. Moreover, the relation between higher-order stress power and heat flux is discussed expressing the first law of thermodynamics with microscopic quantities in the mesodomain. Comparing heat flux with higher-order stress power, it is clarified that the divergence of heat flux is equivalent to the total of each order power due to higher-order stresses.

Numerical Simulation of Confined Nano-Impinging Jet in Microscale Cooling Application Using DSMC Method

2010 ◽  
Author(s):  
M. Darbandi ◽  
H. Akhlaghi ◽  
A. Karchani ◽  
G. E. Schneider
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Constant Temperature ◽  
Pressure Ratio ◽  
Velocity Slip ◽  
Impinging Jet ◽  
Wall Heat Flux ◽  
Geometrical Parameters ◽  
Dsmc Method ◽  
Hot Surface

In this study, we simulate rarefied gas flow through a confined nano-impinging jet using direct simulation Monte Carlo (DSMC) method. The effects of geometrical parameters, pressure ratio, and wall conditions on the heat transfer from a hot surface are examined. Hot surface modeled via diffusive constant wall temperature. Various inlet/confining surface conditions such as specular, adiabatic, and constant temperature are implemented and the effects of them on the wall heat flux rates are studied. The results show that Knudsen number, velocity slip, and temperature jump are main reasons which specify magnitudes of wall heat flux rates. Among all geometrical parameters, H/W ratio has the greatest effect on heat transfer, where H is jet distance from the hot surface and W is the jet width. For different values of pressure ratio, the biggest quantity of wall heat flux rate relates to the lowest velocity slip case. Also for inlet/confining walls with constant temperature condition equal to coolant flow temperature, heat transfer from the hot surface was the maximum.

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