scholarly journals Validation of the direct numerical simulation code based on the criteria of force coefficient convergence

2015 ◽  
Author(s):  
Z. B. Jiang
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Force Coefficient ◽  
Simulation Code

Verification and validation of a Direct Numerical Simulation code

2015 ◽  
Vol 291 ◽  
pp. 266-279 ◽  
Author(s):  
Larissa A. Petri ◽  
Patrícia Sartori ◽  
Josuel K. Rogenski ◽  
Leandro F. de Souza
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Verification And Validation ◽  
Simulation Code

scholarly journals Direct Numerical Simulation of Water Droplets in Turbulent Flow

Fluids ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 158
Author(s):  
Weibo Ren ◽  
Jonathan Reutzsch ◽  
Bernhard Weigand
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flow ◽  
Surface Deformation ◽  
Terminal Velocity ◽  
Wake Flow ◽  
Recirculation Region ◽  
Drop Surface ◽  
Simulation Code ◽  
Axis Ratio

Details on the fall speeds of raindrops are essential in both applications and natural events, such as rain-rate retrieval and soil erosion. Here, we examine the influence of turbulence on the terminal velocity of two water drops of different sizes. For the first time, computations of droplets in turbulent surroundings are conducted with a direct numerical simulation code based on a volume of fluid method. Both the drop surface deformation and internal circulation are captured. The turbulence intensity at the inflow area, as well as the turbulence length scale are varied. In turbulent flow, we find a decline in the terminal velocities for both drops. Based on the study of the wake flow characteristics and drop surface deformation, the decrease in the terminal velocity is found to be directly linked to a shortening of the wake recirculation region resulting from an earlier and more drastic increase in the turbulence kinetic energy in the shear layer. The turbulent surroundings trigger substantial rises in the drop axis ratio amplitude and a slight increase in the drop oscillation frequency, but barely influence the time-averaged drop axis length.

Direct Numerical Simulation of Bubbly Flows and Application to Cavitation Mitigation

2006 ◽  
Vol 129 (5) ◽  
pp. 595-604 ◽  
Author(s):  
Tianshi Lu ◽  
Roman Samulyak ◽  
James Glimm
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Direct Numerical Simulation ◽  
Front Tracking ◽  
Free Surface Flows ◽  
Bubbly Flows ◽  
Simulation Code ◽  
Collapse Pressure ◽  
Cavitation Bubbles ◽  
Bubbly Fluids

The direct numerical simulation (DNS) method has been used to the study of the linear and shock wave propagation in bubbly fluids and the estimation of the efficiency of the cavitation mitigation in the container of the Spallation Neutron Source liquid mercury target. The DNS method for bubbly flows is based on the front tracking technique developed for free surface flows. Our front tracking hydrodynamic simulation code FronTier is capable of tracking and resolving topological changes of a large number of interfaces in two- and three-dimensional spaces. Both the bubbles and the fluid are compressible. In the application to the cavitation mitigation by bubble injection in the SNS, the collapse pressure of cavitation bubbles was calculated by solving the Keller equation with the liquid pressure obtained from the DNS of the bubbly flows. Simulations of the propagation of linear and shock waves in bubbly fluids have been performed, and a good agreement with theoretical predictions and experiments has been achieved. The validated DNS method for bubbly flows has been applied to the cavitation mitigation estimation in the SNS. The pressure wave propagation in the pure and the bubbly mercury has been simulated, and the collapse pressure of cavitation bubbles has been calculated. The efficiency of the cavitation mitigation by bubble injection has been estimated. The DNS method for bubbly flows has been validated through comparison of simulations with theory and experiments. The use of layers of nondissolvable gas bubbles as a pressure mitigation technique to reduce the cavitation erosion has been confirmed.

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