view:41896 Last Update: 2021-9-11
J. Ghazanfarian, D. Jamshideasli, A. Abbassi,
Thermal Lattice Boltzmann Method for Curved Boundaries in the Transition Regime
The three-dimensional thermal lattice Boltzmann (TLBM)-BGK model is developed to simulate the pressure-driven rarefied gaseous flow within a circular channel with constant-temperature-wall in the transition regime (0.1 <Kn<1). D3Q15 model has been employed for velocity discretization. The captured nonlinear behavior of gas in the Knudsen layer (KL), which dominates the flow characteristics in small-scale gaseous flows by modifying the near-wall correction function along with the variation of properties with density and temperature distributions are implemented in a new formulation. An appropriate combination of advanced straight boundary conditions and a 3D extension of an available curved boundary conditions by identifying the nodes either adjacent to the solid nodes or flow nodes on the computational domain with the structured mesh are employed. The results of small-scale phenomena such as slip-velocity and temperature-jump are reported, which are manifestations of the cases with non-zero Kn number. Due to the deficiency of the continuum presumption for high-Knudsen flows, the present study suggests that the TLBM is an efficient tool applicable to the theoretical development of low speed gas flow study, which typically falls within the realm of MEMS/NEMS by virtue of its more straightforward boundary treatments and higher computation capability compared to other atomistic approaches.