A local domain‐free discretization method for simulation of incompressible flows over moving bodies

International Journal of Computational Fluid Dynamics

2015

By introducing a mass source/sink term into the continuity equation, the mass-conservation property of the local domain-free discretisation (DFD) method is improved to reduce the spurious oscillations in the simulation of moving-boundary problems. The mass source/sink term is constructed by evaluating the mass flux through the solid part of the control volume split by the immersed boundary. Additionally, some special treatments are given for the multi-valued nodes associated with thin bodies. The introduction of source/sink term has also been extended to three-dimensional problems. Unlike the ghost-cell immersed boundary method, coupling the mass source/sink algorithm with the local DFD method is implemented on triangular and tetrahedral meshes. Compared to the hybrid reconstruction formulation, the properties of the original local DFD method can be preserved better. Numerical experiments for two-and three-dimensional moving-boundary problems show that the present mass source/sink treatment can reduce spurious oscillations effectively.

Section: Specific Treatment For Cells Associated With Multi-valued Nodesmentioning

confidence: 99%

Section: Mass Source/sink Term Coupling Schemementioning

confidence: 99%

Section: Governing Equations and Basic Numerical Schemesmentioning

confidence: 99%

Section: Governing Equations and Basic Numerical Schemesmentioning

confidence: 99%

See 2 more Smart Citations

Improvement of mass conservation and reduction of spurious oscillations for the local DFD method

Zhang

International Journal of Computational Fluid Dynamics

2015

“…In , Shu and Zhou proposed and developed a nonboundary‐conforming method, called the local domain‐free discretization (DFD) method, to solve partial differential equations. In this method, a partial differential equation is discretized at all mesh points inside the solution domain, but the discrete form at an interior mesh point may involve some points outside the solution domain.…”

Section: Introductionmentioning

confidence: 99%

Mesh adaptation for simulation of unsteady flow with moving immersed boundaries

Numerical Methods in Fluids

2012

SUMMARYIn this work, an approach for performing mesh adaptation in the numerical simulation of two‐dimensional unsteady flow with moving immersed boundaries is presented. In each adaptation period, the mesh is refined in the regions where the solution evolves or the moving bodies pass and is unrefined in the regions where the phenomena or the bodies deviate. The flow field and the fluid–solid interface are recomputed on the adapted mesh. The adaptation indicator is defined according to the magnitude of the vorticity in the flow field. There is no lag between the adapted mesh and the computed solution, and the adaptation frequency can be controlled to reduce the errors due to the solution transferring between the old mesh and the new one. The preservation of conservation property is mandatory in long‐time scale simulations, so a P1‐conservative interpolation is used in the solution transferring. A nonboundary‐conforming method is employed to solve the flow equations. Therefore, the moving‐boundary flows can be simulated on a fixed mesh, and there is no need to update the mesh at each time step to follow the motion or the deformation of the solid boundary. To validate the present mesh adaptation method, we have simulated several unsteady flows over a circular cylinder stationary or with forced oscillation, a single self‐propelled swimming fish, and two fish swimming in the same or different directions. Copyright © 2012 John Wiley & Sons, Ltd.

Simulation of self‐propelled anguilliform swimming by local domain‐free discretization method

Numerical Methods in Fluids

Chen

2011

Self Cite

SUMMARY The local domain‐free discretization method is extended in this work to simulate fluid–structure interaction problems, the class of which is exemplified by the self‐propelled anguilliform swimming of deforming bodies in a fluid medium. Given the deformation of the fish body in its own reference frame, the translational and rotational motions of the body governed by Newton's Law are solved together with the surrounding flow field governed by Navier–Stokes equations. When the body is deforming and moving, no mesh regeneration is required in the computation. The loose coupling strategy is employed to simulate the fluid–structure interaction involved in the self‐propelled swimming. The local domain‐free discretization method and an efficient algorithm for classifying the Eulerian mesh points are described in brief. To validate the fluid–structure interaction solver, we simulate the ‘lock‐in’ phenomena associated with the vortex‐induced vibrations of an elastically mounted cylinder. Finally, we demonstrate applications of the method to two‐dimensional and three‐dimensional anguilliform‐swimming fish. The kinematics and dynamics associated with the center of mass are shown and the rotational movement is also presented via the angular position of the body axis. The wake structure is visualized in terms of vorticity contours. All the obtained numerical results show good agreement with available data in the literature. Copyright © 2011 John Wiley & Sons, Ltd.