UNSTEADY HEAT TRANSFER FROM A CYLINDER IN CROSS FLOW; A DIRECT NUMERICAL SIMULATION

1986 ◽  
Author(s):  
George Em Karniadakis ◽  
Borivoje B. Mikic ◽  
Anthony T. Patera
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Cross Flow ◽  
Unsteady Heat Transfer

Direct numerical simulation of a turbulent jet impinging on a heated wall

2015 ◽  
Vol 764 ◽  
pp. 362-394 ◽  
Author(s):  
T. Dairay ◽  
V. Fortuné ◽  
E. Lamballais ◽  
L.-E. Brizzi
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Nusselt Number ◽  
Direct Numerical Simulation ◽  
Temperature Fields ◽  
Heated Wall ◽  
Small Scale ◽  
Turbulent Regime ◽  
High Heat Transfer ◽  
Radial Evolution

AbstractDirect numerical simulation (DNS) of an impinging jet flow with a nozzle-to-plate distance of two jet diameters and a Reynolds number of 10 000 is carried out at high spatial resolution using high-order numerical methods. The flow configuration is designed to enable the development of a fully turbulent regime with the appearance of a well-marked secondary maximum in the radial distribution of the mean heat transfer. The velocity and temperature statistics are validated with documented experiments. The DNS database is then analysed focusing on the role of unsteady processes to explain the spatial distribution of the heat transfer coefficient at the wall. A phenomenological scenario is proposed on the basis of instantaneous flow visualisations in order to explain the non-monotonic radial evolution of the Nusselt number in the stagnation region. This scenario is then assessed by analysing the wall temperature and the wall shear stress distributions and also through the use of conditional averaging of velocity and temperature fields. On one hand, the heat transfer is primarily driven by the large-scale toroidal primary and secondary vortices emitted periodically. On the other hand, these vortices are subjected to azimuthal distortions associated with the production of radially elongated structures at small scale. These distortions are responsible for the appearance of very high heat transfer zones organised as cold fluid spots on the heated wall. These cold spots are shaped by the radial structures through a filament propagation of the heat transfer. The analysis of probability density functions shows that these strong events are highly intermittent in time and space while contributing essentially to the secondary peak observed in the radial evolution of the Nusselt number.

scholarly journals HEAT EXCHANGE IN A PLANE CHANNEL IN A TURBULENT FLOW REGIME IN THE CASE OF SMALL VALUES OF PRANDTL NUMBER ACCORDING TO DATA OF DIRECT NUMERICAL SIMULATION

2021 ◽  
Vol 56 ◽  
pp. 57-60
Author(s):  
Yurii G. Chesnokov ◽  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Prandtl Number ◽  
Direct Numerical Simulation ◽  
Transfer Process ◽  
Peclet Number ◽  
Plane Channel ◽  
Heat Transfer Process ◽  
Flat Channel ◽  
Péclet Number

Using the results obtained by the method of direct numerical simulation of the heat transfer process in a flat channel by various authors, it is shown that at small values of Prandtl number quite a few characteristics of the heat transfer process in a flat channel depend not on Reynolds and Prandtl numbers separately, but on Peclet number. Peclet number is calculated from the so-called dynamic speed

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