A NUMERICAL STUDY ON PREMIXED MICROCOMBUSTION BY LATTICE BOLTZMANN METHOD

2012 ◽  
Vol 23 (05) ◽  
pp. 1250037 ◽  
Author(s):  
ZHIWEI TIAN ◽  
YUNLIANG TAN ◽  
SHENG CHEN

Lattice Boltzmann method (LBM) has made great progress in the last decade, and its application became wider and wider. In this paper, based on our former combustion LBM model on the macroscale, we attempt to extend it into premixed microcombustion simulation. Considering the external heat losses in microcombustion, the second-order implicit scheme for boundary condition treatment was adopted in our LBM model. Numerical tests have proved that its accuracy and stability were suitable. Furthermore, planar microcombustion with backward-facing step was also studied in order to show its different performances and improvement, which are compared with microcombustor without back step.

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yi Zhu ◽  
Fang-Bao Tian ◽  
John Young ◽  
James C. Liao ◽  
Joseph C. S. Lai

AbstractFish adaption behaviors in complex environments are of great importance in improving the performance of underwater vehicles. This work presents a numerical study of the adaption behaviors of self-propelled fish in complex environments by developing a numerical framework of deep learning and immersed boundary–lattice Boltzmann method (IB–LBM). In this framework, the fish swimming in a viscous incompressible flow is simulated with an IB–LBM which is validated by conducting two benchmark problems including a uniform flow over a stationary cylinder and a self-propelled anguilliform swimming in a quiescent flow. Furthermore, a deep recurrent Q-network (DRQN) is incorporated with the IB–LBM to train the fish model to adapt its motion to optimally achieve a specific task, such as prey capture, rheotaxis and Kármán gaiting. Compared to existing learning models for fish, this work incorporates the fish position, velocity and acceleration into the state space in the DRQN; and it considers the amplitude and frequency action spaces as well as the historical effects. This framework makes use of the high computational efficiency of the IB–LBM which is of crucial importance for the effective coupling with learning algorithms. Applications of the proposed numerical framework in point-to-point swimming in quiescent flow and position holding both in a uniform stream and a Kármán vortex street demonstrate the strategies used to adapt to different situations.


Author(s):  
Mohamed El Amine Ben Amara ◽  
Patrick Perré ◽  
Abdolreza Kharaghani ◽  
Sassi Ben Nasrallah

Author(s):  
Joris C. G. Verschaeve

By means of the continuity equation of the incompressible Navier–Stokes equations, additional physical arguments for the derivation of a formulation of the no-slip boundary condition for the lattice Boltzmann method for straight walls at rest are obtained. This leads to a boundary condition that is second-order accurate with respect to the grid spacing and conserves mass. In addition, the boundary condition is stable for relaxation frequencies close to two.


2003 ◽  
Vol 17 (01n02) ◽  
pp. 139-143
Author(s):  
GÁBOR HÁZI ◽  
ISTVÁN FARKAS

In this paper, we present a numerical study of the Jeffery-Hammel problem using the lattice-Boltzmann method. We study three situations: pure inflow, pure outflow, and outflow with backflow. We demonstrate that the lattice-Boltzmann method gives not only qualitatively but also quantitatively accurate solutions for this problem. From the point of view of stability of the flow, the recent results of bifurcation theory are also briefly considered from the viewpoint of our numerical results.


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