Application of Combination of Local Domain Free Discretization and Immersed Boundary Method (LDFD-IBM) to Numerical Simulation of 3D Flows Over a Circular Cylinder

2014 ◽  
Author(s):  
Yanling Wu ◽  
Chang Shu ◽  
Johan Gullman-Strand

In this paper, the recent developed Local Domain Free Discretization method combined with Immersed Boundary Method (called LDFD-IBM) is extended from two-dimensional version to three-dimensional version. LDFD-IBM is a new member in the family of Cartesian mesh methods. The advantages of LDFD-IBM over other Cartesian mesh solvers includes: no cutting cell, easy to adaptive mesh refinement, easy to implement for moving boundary problems, truly second order accuracy over whole domain, no flow penetration into the solid wall. LDFD-IBM three-dimensional solver is then used to simulate three-dimensional flow past a circular cylinder. Both oblique mode and parallel mode of vortex shedding of the cylinder in three-dimensional configuration are reproduced according to different end-conditions. Oblique shedding is one of the important three-dimensional features that could influence the amplitude, frequency and phase of the flow-induced forces.

Author(s):  
Z. Wei ◽  
Z. C. Zheng

The immersed boundary methods are well known as an efficient flow solver for engineering problems involving fluid structure interactions. However, in order to obtain better results, higher resolutions near the immersed boundary points are desired. Non-uniform Cartesian mesh can easily fulfill this task without introducing a dramatic increase on the cost of computation and coding. In the current paper, an immersed boundary method with non-uniform Cartesian mesh is demonstrated. The Poisson problem is solved with assistance of a scientific parallel computational library PETSc. The code is validated with a three-dimensional flow over a stationary sphere. Then, a fluid-structure interaction model is coupled and validated with two-dimensional vortex induced vibration problems. Comparisons with previous studies are presented. The ultimate goal is to couple the fluid-structure interaction model with the three-dimensional immersed boundary method.


2021 ◽  
Vol 233 ◽  
pp. 109189
Author(s):  
Bin Yan ◽  
Wei Bai ◽  
Sheng-Chao Jiang ◽  
Peiwen Cong ◽  
Dezhi Ning ◽  
...  

2012 ◽  
Vol 140 (5) ◽  
pp. 1603-1619 ◽  
Author(s):  
Yu-Chieng Liou ◽  
Shao-Fan Chang ◽  
Juanzhen Sun

This study develops an extension of a variational-based multiple-Doppler radar synthesis method to construct the three-dimensional wind field over complex topography. The immersed boundary method (IBM) is implemented to take into account the influence imposed by a nonflat surface. The IBM has the merit of providing realistic topographic forcing without the need to change the Cartesian grid configuration into a terrain-following coordinate system. Both Dirichlet and Neumann boundary conditions for the wind fields can be incorporated. The wind fields above the terrain are obtained by variationally adjusting the solutions to satisfy a series of weak constraints, which include the multiple-radar radial velocity observations, anelastic continuity equation, vertical vorticity equation, background wind, and spatial smoothness terms. Experiments using model-simulated data reveal that the flow structures over complex orography can be successfully retrieved using radial velocity measurements from multiple Doppler radars. The primary advantages of the original synthesis method are still maintained, that is, the winds along and near the radar baseline are well retrieved, and the resulting three-dimensional flow fields can be used directly for vorticity budget diagnosis. If compared with the traditional wind synthesis algorithm, this method is able to merge data from different sources, and utilize data from any number of radars. This provides more flexibility in designing various scanning strategies, so that the atmosphere may be probed more efficiently using a multiple-radar network. This method is also tested using the radar data collected during the Southwest Monsoon Experiment (SoWMEX), which was conducted in Taiwan from May to June 2008 with reasonable results being obtained.


Author(s):  
T. X. Dinh

The immediate aim of this study is to check the accuracy of Kajishima’s method (one kind of immersed boundary method) for the direct numerical simulation (DNS) of turbulent channel flow over a complicated bed. In this paper, the simulation of three dimensional, time -dependent turbulent flows over a fixed hemisphere at the bed of an open channel is carried out. A finite different method (FDM) is applied with a staggered Cartesian mesh. The forces, the moments about the center of the hemisphere, and the distribution of pressure on the hemisphere in the plane of symmetry are calculated.


Computation ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 50
Author(s):  
Jonatas Borges ◽  
Marcos Lourenço ◽  
Elie Padilla ◽  
Christopher Micallef

The immersed boundary method has attracted considerable interest in the last few years. The method is a computational cheap alternative to represent the boundaries of a geometrically complex body, while using a cartesian mesh, by adding a force term in the momentum equation. The advantage of this is that bodies of any arbitrary shape can be added without grid restructuring, a procedure which is often time-consuming. Furthermore, multiple bodies may be simulated, and relative motion of those bodies may be accomplished at reasonable computational cost. The numerical platform in development has a parallel distributed-memory implementation to solve the Navier-Stokes equations. The Finite Volume Method is used in the spatial discretization where the diffusive terms are approximated by the central difference method. The temporal discretization is accomplished using the Adams-Bashforth method. Both temporal and spatial discretizations are second-order accurate. The Velocity-pressure coupling is done using the fractional-step method of two steps. The present work applies the immersed boundary method to simulate a Newtonian laminar flow through a three-dimensional sudden contraction. Results are compared to published literature. Flow patterns upstream and downstream of the contraction region are analysed at various Reynolds number in the range 44 ≤ R e D ≤ 993 for the large tube and 87 ≤ R e D ≤ 1956 for the small tube, considerating a contraction ratio of β = 1 . 97 . Comparison between numerical and experimental velocity profiles has shown good agreement.


Author(s):  
Claudia Günther ◽  
Matthias Meinke ◽  
Wolfgang Schröder

In this work, a Cartesian-grid immersed boundary method using a cut-cell approach is applied to three-dimensional in-cylinder flow. A hierarchically coupled level-set solver is used to capture the boundary motion by a signed distance function. Topological changes in the geometry due to the opening and closing events of the valves are modeled consistently using multiple signed distance functions for the different components of the engine and taking advantage of a level-set reinitialization method. A continuous discretization of the flow equations in time near the moving interfaces is used to prevent nonphysical oscillations. To ensure an efficient implementation, independent grid adaptation for the flow and the level-set grid is applied. A narrow band approach and an efficient joining/splitting algorithm for the level-set functions minimize the computational overhead to track multiple interfaces. The ability of the current method to handle complex 3D setups is demonstrated for the interface capturing and the flow solution in a three-dimensional piston engine geometry.


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