Application of the Immersed Boundary Method and Direct Numerical Simulation for the Heat Transfer From Particles

2009 ◽  
Author(s):  
Zhi-Gang Feng ◽  
Efstathios E. Michaelides
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Density Function ◽  
Fluid Phase ◽  
Solid Particles ◽  
Computational Method ◽  
Immersed Boundary ◽  
Force Density ◽  
Particulate Flows

A combination of the Direct Numerical Simulation (DNS) with the Immersed Boundary (IB) method has been developed to solve the momentum and heat transfer equations for the computation of thermal convection in particulate flows. This numerical method makes use of a finite difference method in and uses a regular Eulerian grid to solve the modified momentum and energy equations for the entire flow region simultaneously. In the region that is occupied by the solid particles, a second particle-based Lagrangian grid is used, which tracks all the particles, and a force density function or an energy density function is introduced to represent the momentum interaction or thermal interaction between the particulate phase and fluid phase. The numerical methods presented have been validated by comparing the results of the simulation with similar numerical results obtained by others. Among the advantages of this computational method is that it may be used for the determination, stipulation and validation of boundary conditions in particulate flows that may be used with larger Eulerian codes.

An Immersed Boundary Based Method for Studying Thermal Interaction of Particles in a Viscous Fluid

2010 ◽  
Author(s):  
Zhi-Gang Feng ◽  
Basu D. Paudel ◽  
Xing Zhang
Keyword(s):  
Heat Transfer ◽  
Viscous Fluid ◽  
Density Function ◽  
Particle Surface ◽  
Flow Region ◽  
Solid Particles ◽  
Immersed Boundary ◽  
Force Density ◽  
Thermal Interaction ◽  
Surrounding Fluid

The results of thermal interactions between a solid particle and a fluid have two folds: the motion of fluid affects the heat transfer and energy balance of a particle; and the heat transfer from particles influences the fluid motion. When the temperature of a particle and its surrounding fluid is not the same, heat is transferred between the particle and the fluid. The heat flux influences the properties of the surrounding fluid and changes the dynamics of the sedimentation of the particle. To study the effect of non-isothermal flows to the motion of a particle, we have developed a Direct Numerical Simulation (DNS) method that is capable of solving both the momentum equation and heat transfer equation for the computation of thermal interaction between particles and fluid. This numerical method makes use of a finite difference method in combination with the Immersed Boundary (IB) method for treating the particulate phase. In particular, the IB concept has been extended to treat thermal boundary condition at the particle surface. A regular Eulerian grid is used to solve the modified momentum and energy equations for the entire flow region simultaneously. In the region that is occupied by the solid particles, a second particle-based Lagrangian grid is used, which tracks particles, and a force density function or an energy density function is introduced to represent the momentum interaction or thermal interaction between particle and fluid. In this paper, the IB based DNS method has been applied to study the fluidization of 12,000 circular particles, the unsteady conduction of a sphere in a stagnant fluid, and the sedimentation of a non-isothermal sphere in a viscous fluid at different Grashof number. Our simulation results show that the sedimentation velocity of the particle depends strongly on the thermal interaction of particle and fluid due to the strong buoyancy force exerted on the particle.

Direct Numerical Simulation of Particle Heat and Mass Transfer in a Fluidized Bed

2014 ◽  
Author(s):  
Zhi-Gang Feng ◽  
Adam Roig
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Fluidized Bed ◽  
Immersed Boundary Method ◽  
Fluid Velocity ◽  
Temperature Fields ◽  
Immersed Boundary ◽  
Boundary Method ◽  
Study Heat Transfer

We have developed a Direct Numerical Simulation combined with the Immersed Boundary method (DNS-IB) to study heat transfer in particulate flows. In this method, fluid velocity and temperature fields are obtained by solving the modified momentum and heat transfer equations, which result from the presence of heated particles in the fluid; particles are tracked individually and their velocities and positions are solved based on the equations of linear and angular motions; particle temperature is assumed to be a constant. The momentum and heat exchanges between a particle and the surrounding fluid at its surface are resolved using the immersed boundary method with the direct forcing scheme. The DNS-IB method has been used to study heat transfer of 1024 of heated spheres in a fluidized bed. By exploring the rich data generated from the DNS-IB simulations, we are able to obtain statistically averaged fluid and particle velocity as well as overall heat transfer rate in a fluidized bed.

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