On the Propulsive Performance of Tandem Flapping Wings with a Modified Immersed Boundary Method

2016 ◽  
Vol 13 (05) ◽  
pp. 1650025 ◽  
Author(s):  
Dingyi Pan ◽  
Jian Deng ◽  
Xueming Shao ◽  
Zubin Liu
Keyword(s):  
Immersed Boundary Method ◽  
Thrust Force ◽  
Wake Flow ◽  
Flapping Wings ◽  
Immersed Boundary ◽  
Phase Lag ◽  
Boundary Method ◽  
Total Thrust ◽  
Tandem Flapping Wings ◽  
The One

The modified immersed boundary method is introduced and applied to study the propulsive mechanism of a tandem flapping wings system. The effects of tandem wings distance and phase lag between the two flapping wings are investigated. Thrust force of the upstream wing is nearly constant and close to the magnitude of single flapping wing system. Thrust force of second wing is influenced by the distance and phase lag. With specific parameters, the second wing can obtain a maximum thrust which is larger than the one of first wing. The flow structures of the wake flow are classified into three different formations, and they are correlated to the trends of thrust force. The effects of distance and phase lag are coupled other than isolated. It is possible to lower down the power consumption of this tandem flapping wings system and enhance the total thrust force of the system at the same time.

Direct Numerical Simulation of Turbulent Flows in Rough Pipes Using an Immersed Boundary Method With a Spectral Representation of the Roughness Topography

2010 ◽  
Author(s):  
A. T. van Nimwegen ◽  
L. M. Portela
Keyword(s):  
Turbulent Flow ◽  
Turbulent Flows ◽  
Immersed Boundary Method ◽  
Spectral Representation ◽  
Axial Direction ◽  
Immersed Boundary ◽  
Azimuthal Direction ◽  
Boundary Method ◽  
The One ◽  
Wall Geometry

An immersed boundary method, similar to the one used by Kim et al. [1] was developed to implement a varying wall topography into an existing DNS code for pipe flow. Validation using a semi-analytical solution and numerical results showed that the method yields accurate results for laminar flow. Four simulations for turbulent flow where performed, each with a different wall geometry. Wall topographies varying in the axial direction and topographies varying in the azimuthal direction have been considered. Time-averaged as well as instantaneous results are presented for the different geometries. The results for turbulent flow are consistent with the expected physical behaviour. They confirm the hypothesis that flow in the outer layer is largely unaffected by the wall topography.

scholarly journals Direct Numerical Simulation of Gas–Particle Flows with Particle–Wall Collisions Using the Immersed Boundary Method

2018 ◽  
Vol 8 (12) ◽  
pp. 2387 ◽  
Author(s):  
Yusuke Mizuno ◽  
Shun Takahashi ◽  
Kota Fukuda ◽  
Shigeru Obayashi
Keyword(s):  
Immersed Boundary Method ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Navier Stokes Equation ◽  
Level Set Function ◽  
Boundary Method ◽  
The One ◽  
Energy And Momentum

We investigated particulate flows by coupling simulations of the three-dimensional incompressible Navier–Stokes equation with the immersed boundary method (IBM). The results obtained from the two-way coupled simulation were compared with those of the one-way simulation, which is generally applied for clarifying the particle kinematics in industry. In the present flow simulation, the IBM was solved using a ghost–cell approach and the particles and walls were defined by a level set function. Using proposed algorithms, particle–particle and particle–wall collisions were implemented simply; the subsequent coupling simulations were conducted stably. Additionally, the wake structures of the moving, colliding and rebounding particles were comprehensively compared with previous numerical and experimental results. In simulations of 50, 100, 200 and 500 particles, particle–wall collisions were more frequent in the one–way scheme than in the two-way scheme. This difference was linked to differences in losses in energy and momentum.

Simulations of High Reynolds Number Air Flow Over the NACA-0012 Airfoil Using the Immersed Boundary Method

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
James P. Johnson ◽  
Gianluca Iaccarino ◽  
Kuo-Huey Chen ◽  
Bahram Khalighi
Keyword(s):  
Immersed Boundary Method ◽  
Aerodynamic Force ◽  
Leading Edge ◽  
Wake Flow ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Boundary Method ◽  
Computational Mesh ◽  
High Reynolds ◽  
Naca 0012

The immersed-boundary method is coupled to an incompressible-flow Reynolds-averaged Navier Stokes solver, based on a two-equation turbulence model, to perform unsteady numerical simulations of airflow past the NACA-0012 airfoil for several angles of attack and Reynolds numbers of 5.0×105 and 1.8×106. A preliminary study is performed to evaluate the sensitivity of the calculations to the computational mesh and to guide the creation of the computational cells for the unsteady calculations. Qualitative characterizations of the flow in the vicinity of the airfoil are obtained to assess the capability of locally refined grids to capture the thin boundary layers close to the airfoil leading edge as well as the wake flow emanating from the trailing edge. Quantitative analysis of aerodynamic force coefficients and wall pressure distributions are also reported and compared to experimental results and those from body-fitted grid simulations using the same solver to assess the accuracy and limitations of this approach. The immersed-boundary simulations compared well to the experimental and body-fitted results up to the occurrence of separation. After that point, neither computational approach provided satisfactory solutions.

A High-Order Immersed-Boundary Method for Complex/Moving Boundaries

2014 ◽  
Author(s):  
Chi Zhu ◽  
Guibo Li ◽  
Haoxiang Luo
Keyword(s):  
Immersed Boundary Method ◽  
Numerical Approach ◽  
High Order ◽  
Moving Boundaries ◽  
Immersed Boundary ◽  
Third Order ◽  
Compact Finite Difference Scheme ◽  
Boundary Method ◽  
The One ◽  
Immersed Boundaries

In this study, we intend to develop a high-order numerical approach using the immersed-boundary method to solve problems with complex and moving boundaries such as biological locomotion (animal swimming and flying) and biomedical flow systems. The basic idea is to use the compact finite-difference scheme to resolve the flow field and a higher-order forcing scheme to treat the immersed boundaries. In this work, the one-dimensional formulation of the numerical approach is presented and is tested extensively for its convergence. Such tests are necessary before more complicated tests in 2D/3D. An overall third-order accuracy is achieved as desired. Extension to higher dimensions is ongoing.

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