Boundary condition-enforced immersed boundary method for thermal flow problems with Dirichlet temperature condition and its applications

2012 ◽  
Vol 57 ◽  
pp. 40-51 ◽  
Author(s):  
W.W. Ren ◽  
C. Shu ◽  
J. Wu ◽  
W.M. Yang
Keyword(s):  
Boundary Condition ◽  
Immersed Boundary Method ◽  
Immersed Boundary ◽  
Thermal Flow ◽  
Flow Problems ◽  
Boundary Method

A boundary condition-enforced immersed boundary method for compressible viscous flows

2016 ◽  
Vol 136 ◽  
pp. 104-113 ◽  
Author(s):  
Y.L. Qiu ◽  
C. Shu ◽  
J. Wu ◽  
Y. Sun ◽  
L.M. Yang ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Immersed Boundary Method ◽  
Viscous Flows ◽  
Immersed Boundary ◽  
Boundary Method ◽  
Compressible Viscous Flows

Large-Eddy Simulation over Complex Terrain Using an Improved Immersed Boundary Method in the Weather Research and Forecasting Model

2018 ◽  
Vol 146 (9) ◽  
pp. 2781-2797 ◽  
Author(s):  
Jingyi Bao ◽  
Fotini Katopodes Chow ◽  
Katherine A. Lundquist
Keyword(s):  
Boundary Condition ◽  
Immersed Boundary Method ◽  
Complex Terrain ◽  
Weather Research And Forecasting ◽  
Immersed Boundary ◽  
Flat Terrain ◽  
Boundary Method ◽  
Terrain Following ◽  
Bolund Hill ◽  
Askervein Hill

Abstract The Weather Research and Forecasting (WRF) Model is increasingly being used for higher-resolution atmospheric simulations over complex terrain. With increased resolution, resolved terrain slopes become steeper, and the native terrain-following coordinates used in WRF result in numerical errors and instability. The immersed boundary method (IBM) uses a nonconformal grid with the terrain surface represented through interpolated forcing terms. Lundquist et al.’s WRF-IBM implementation eliminates the limitations of WRF’s terrain-following coordinate and was previously validated with a no-slip boundary condition for urban simulations and idealized terrain. This paper describes the implementation of a log-law boundary condition into WRF-IBM to extend its applicability to general atmospheric complex terrain simulations. The implementation of the improved WRF-IBM boundary condition is validated for neutral flow over flat terrain and the complex terrain cases of Askervein Hill, Scotland, and Bolund Hill, Denmark. First, comparisons are made to similarity theory and standard WRF results for the flat terrain case. Then, simulations of flow over the moderately sloped Askervein Hill are used to demonstrate agreement between the IBM and terrain-following WRF results, as well as agreement with observations. Finally, Bolund Hill simulations show that WRF-IBM can handle steep topography (standard WRF fails) and compares well to observations. Overall, the new WRF-IBM boundary condition shows improved performance, though the leeside representation of the flow can be potentially further improved.

Terrain Effects on Wind Flow: Simulations With an Immersed Boundary Method

2011 ◽  
Author(s):  
S. Jafari ◽  
N. Chokani ◽  
R. S. Abhari
Keyword(s):  
Boundary Condition ◽  
Immersed Boundary Method ◽  
Flow Simulation ◽  
Rectangular Domain ◽  
Immersed Boundary ◽  
Wind Flow ◽  
Generation Process ◽  
Wind Rose ◽  
Boundary Method ◽  
Arbitrary Topography

The modelling of the wind resource over arbitrary topography is required to optimize the micrositing of wind turbines. Most solvers use classical body-fitted grid for simulations. In such an approach, to cover the wind rose using a rectangular domain, a dedicated mesh must be generated for each direction. Moreover, over complex terrain, additional numerical errors are introduced in the solver due to coordinate transformations. To overcome these challenges and to facilitate the grid generation process, an immersed boundary method is developed in connection with a RANS solver in order to simulate turbulent atmospheric flows over arbitrary topography. In this method, a Cartesian grid is used and the boundary condition on the terrain surface is modelled within the solver using a “direct forcing” approach. With the immersed boundary method a rectangular grid can be used to simulate the flow field for all wind directions and only a rotation of the digital elevation map is required. Ghost cells are used to enforce the desired boundary condition at the immersed surface. The immersed boundary method developed in this work is used to simulate the flow in connection with both Baldwin-Lomax and kω turbulence models. The performance of the method is examined for the flow over a two-dimensional hill. Results are compared with experimental data as well as a classical body-fitted grid to isolate the effect of the boundary conditions. The comparisons show good agreement among all the results. The results for the three-dimensional wind flow simulation over the Askervein Hill test case are also presented, and show the capability of the immersed boundary method in a full-scale scenario.

scholarly journals Simulation of Thermal Flow Problems via a Hybrid Immersed Boundary-Lattice Boltzmann Method

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
J. Wu ◽  
C. Shu ◽  
N. Zhao
Keyword(s):  
Boundary Condition ◽  
Temperature Field ◽  
Heat Source ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Source Term ◽  
Immersed Boundary ◽  
Thermal Flow ◽  
Flow Problems ◽  
Boltzmann Method

A hybrid immersed boundary-lattice Boltzmann method (IB-LBM) is presented in this work to simulate the thermal flow problems. In current approach, the flow field is resolved by using our recently developed boundary condition-enforced IB-LBM (Wu and Shu, (2009)). The nonslip boundary condition on the solid boundary is enforced in simulation. At the same time, to capture the temperature development, the conventional energy equation is resolved. To model the effect of immersed boundary on temperature field, the heat source term is introduced. Different from previous studies, the heat source term is set as unknown rather than predetermined. Inspired by the idea in (Wu and Shu, (2009)), the unknown is calculated in such a way that the temperature at the boundary interpolated from the corrected temperature field accurately satisfies the thermal boundary condition. In addition, based on the resolved temperature correction, an efficient way to compute the local and average Nusselt numbers is also proposed in this work. As compared with traditional implementation, no approximation for temperature gradients is required. To validate the present method, the numerical simulations of forced convection are carried out. The obtained results show good agreement with data in the literature.

An Efficient Immersed Boundary-Lattice Boltzmann Method for the Simulation of Thermal Flow Problems

2016 ◽  
Vol 20 (5) ◽  
pp. 1210-1257 ◽  
Author(s):  
Yang Hu ◽  
Decai Li ◽  
Shi Shu ◽  
Xiaodong Niu
Keyword(s):  
Natural Convection ◽  
Boundary Conditions ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Immersed Boundary Method ◽  
Immersed Boundary ◽  
Thermal Flow ◽  
Flow Problems ◽  
Thermal Boundary Conditions ◽  
Boltzmann Method

AbstractIn this paper, a diffuse-interface immersed boundary method (IBM) is proposed to treat three different thermal boundary conditions (Dirichlet, Neumann, Robin) in thermal flow problems. The novel IBM is implemented combining with the lattice Boltzmann method (LBM). The present algorithm enforces the three types of thermal boundary conditions at the boundary points. Concretely speaking, the IBM for the Dirichlet boundary condition is implemented using an iterative method, and its main feature is to accurately satisfy the given temperature on the boundary. The Neumann and Robin boundary conditions are implemented in IBM by distributing the jump of the heat flux on the boundary to surrounding Eulerian points, and the jump is obtained by applying the jump interface conditions in the normal and tangential directions. A simple analysis of the computational accuracy of IBM is developed. The analysis indicates that the Taylor-Green vortices problem which was used in many previous studies is not an appropriate accuracy test example. The capacity of the present thermal immersed boundary method is validated using four numerical experiments: (1) Natural convection in a cavity with a circular cylinder in the center; (2) Flows over a heated cylinder; (3) Natural convection in a concentric horizontal cylindrical annulus; (4) Sedimentation of a single isothermal cold particle in a vertical channel. The numerical results show good agreements with the data in the previous literatures.

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