scholarly journals Large Eddy Simulation of Vortex Structures and Frequency Characteristics in Turbulent Flow through an Axisymmetric Sudden Expansion

2007 ◽  
Vol 73 (727) ◽  
pp. 751-758 ◽  
Author(s):  
Hideki YANAOKA ◽  
Takao INAMURA ◽  
Takanori SHIMOMACHI
2020 ◽  
Vol 6 (4) ◽  
Author(s):  
N. Satish ◽  
K. Venkatasubbaiah

Abstract Pulsation and acceleration of liquid metal turbulent flow through a horizontal channel has been numerically studied using a large eddy simulation (LES) technique. The effect of inlet pulsation and acceleration on flow and heat transfer characteristics of low Prandtl number liquid metal flow have been investigated and reported here. Results have been presented for different Reynolds numbers, different amplitudes, and frequency with constant bottom wall thickness. The flow field is modeled as unsteady-state two-dimensional incompressible turbulent-forced convection flow. Turbulence is modeled using a LES technique. Two-dimensional unsteady-state heat conduction equation is solved to know the temperature distribution in the solid region. Finite difference method solver is developed for solving the governing equations using sixth-order accuracy of compact schemes. The average Nusselt number shows cyclic variation with respect to time in pulsation flows. The enhancement of heat transfer with pulsation at amplitude 0.4 and frequency 100 Hz is 6.51%. The rate of heat transfer increases in pulsation flow compared to quasi-steady flow. The inlet acceleration shows a significant effect on flow characteristics. The present results are compared with direct numerical simulation (DNS) results available in the literature and matching well with DNS data.


2009 ◽  
Vol 78 (3) ◽  
pp. 347-365 ◽  
Author(s):  
Thorsten Stoesser ◽  
Guillermo Palau Salvador ◽  
Wolfgang Rodi ◽  
Panayiotis Diplas

Author(s):  
Emad Y. Tanbour ◽  
Ramin K. Rahmani ◽  
Anahita Ayasoufi

Small orifices are widely used in different industries including gas appliances. Although characteristics of orifices such as their coefficient of discharge have been subject of interest for the past several decades, most of the previous studies focus on relatively high Reynolds number flow through relatively large diameter orifices. Moreover, the majority of previous work has focused on incompressible flows. This study focuses on the flow of different compressible gaseous fluids inside small orifices ranging from 1.3 mm to 2.1 mm hydraulic diameters for flow Re numbers of ∼8000 to ∼26000. Large-Eddy Simulation for turbulent flow is employed to solve the second-order discrete equations for compressible and incompressible flows in gas appliance orifices to predict the flow characteristics for relatively low-Re compressible flows in orifices widely used in gas appliance industry. The impacts of fluid material, the orifice hydraulic diameter, and the orifice profile on the characteristics of orifice are studied.


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