Role of fluid heating in dense gas–solid flow as revealed by particle-resolved direct numerical simulation

2013 ◽  
Vol 58 (1-2) ◽  
pp. 471-479 ◽  
Author(s):  
S. Tenneti ◽  
B. Sun ◽  
R. Garg ◽  
S. Subramaniam
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Dense Gas ◽  
Solid Flow

Direct Numerical Simulation of Drops in Three Dimensional Viscoelastic Simple Shear Flows

2001 ◽  
Author(s):  
Shriram B. Pillapakkam ◽  
Pushpendra Singh
Keyword(s):  
Numerical Simulation ◽  
Shear Flow ◽  
Direct Numerical Simulation ◽  
Viscoelastic Fluid ◽  
Simple Shear ◽  
Polymer Concentration ◽  
Three Dimensional ◽  
Simple Shear Flow ◽  
Splitting Technique

Abstract A three dimensional finite element scheme for Direct Numerical Simulation (DNS) of viscoelastic two phase flows is implemented. The scheme uses the Level Set Method to track the interface and the Marchuk-Yanenko operator splitting technique to decouple the difficulties associated with the governing equations. Using this numerical scheme, the shape of Newtonian drops in a simple shear flow of viscoelastic fluid and vice versa are analyzed as a function of Capillary number, Deborah number and polymer concentration. The viscoelastic fluid is modeled via the Oldroyd-B model. The role of viscoelastic stresses in deformation of a drop subjected to simple shear flow and its effect on the steady state shape is analyzed. Our results compare favorably with existing experimental data and also help in understanding the role of viscoelastic stresses in drop deformation.

The influence of entropy fluctuations on the interaction of turbulence with a shock wave

1997 ◽  
Vol 334 ◽  
pp. 353-379 ◽  
Author(s):  
KRISHNAN MAHESH ◽  
SANJIVA K. LELE ◽  
PARVIZ MOIN
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Kinetic Energy ◽  
Direct Numerical Simulation ◽  
Scaling Law ◽  
Linear Analysis ◽  
Turbulent Field ◽  
Bulk Compression ◽  
Baroclinic Torque

Direct numerical simulation and inviscid linear analysis are used to study the interaction of a normal shock wave with an isotropic turbulent field of vorticity and entropy fluctuations. The role of the upstream entropy fluctuations is emphasized. The upstream correlation between the vorticity and entropy fluctuations is shown to strongly influence the evolution of the turbulence across the shock. Negative upstream correlation between u′ and T′ is seen to enhance the amplification of the turbulence kinetic energy, vorticity and thermodynamic fluctuations across the shock wave. Positive upstream correlation has a suppressing effect. An explanation based on the relative effects of bulk compression and baroclinic torque is proposed, and a scaling law is derived for the evolution of vorticity fluctuations across the shock. The validity of Morkovin's hypothesis across a shock wave is examined. Linear analysis is used to suggest that shock-front oscillation would invalidate the relation between urms and Trms, as expressed by the hypothesis.

The Analysis of Direct Numerical Simulation and Experiment in Critical Point of Transitional Flow

2014 ◽  
Vol 1046 ◽  
pp. 196-199
Author(s):  
Jun Wang ◽  
Guang Sheng Du ◽  
Yong Hui Liu
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Critical Point ◽  
Transitional Flow ◽  
Viscous Force ◽  
Wall Region ◽  
Flow State ◽  
Transitional Area ◽  
Simulation And Experiment

In order to study the lower critical point in transitional area of pipe, we used the method of direct numerical simulation to simulate fluid flow and contrasted it with experiment. The result showed that the flow state is close to laminar. Along the pipe axis, the change of pressure is not obviously. The changing rate of axial velocity U near wall region was significantly greater than in the mainstream area, it proved the important role of viscous force.

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