Numerical Simulation Method for 3D Low Speed Micro Flapping-Wing with Complex Kinematics

2011 ◽  
Vol 308-310 ◽  
pp. 332-335
Author(s):  
Wen Qing Yang ◽  
Bi Feng Song ◽  
Wen Ping Song ◽  
Zhan Ke Li ◽  
Ya Feng Zhang
Keyword(s):  
Numerical Simulation ◽  
Numerical Method ◽  
Stokes Equations ◽  
Simulation Method ◽  
Flapping Wing ◽  
Design Tool ◽  
Navier Stokes ◽  
Low Speed ◽  
Wing Motion ◽  
Numerical Simulation Method

A numerical simulation method is presented in this paper for 3D low speed micro flapping-wing with complex kinematics. The main characteristics for the numerical simulation of Flapping-wing Micro Air Vehicle (FMAV) include: low speed, big range of wing motion, and complex kinematics. The low speed problem is solved by preconditioning method. The big range of wing motion problem is solved by chimera grid system. The problem of complex kinematics is solved by decomposed into three main motions, i.e. plunging, pitching, and swing respectively. The numerical method is solving the Reynolds Averaged Navier-Stokes equations for the viscous flow over micro flapping-wing. The numerical method of this paper is validated by good accordance with experimental results of reference. This method can used to simulate the aerodynamic performance of micro flapping-wing with complex kinematics in low speed and is helpful to the FMAV designers as a design tool.

Effect of Plenum Chamber Configuration on Airflow Uniformity in Unidirectional Flow Cleanrooms

1994 ◽  
Vol 37 (4) ◽  
pp. 21-27
Author(s):  
Guoping Xie ◽  
Yoshihide Suwa
Keyword(s):  
Numerical Simulation ◽  
Numerical Method ◽  
Pressure Loss ◽  
Simulation Method ◽  
Calculation Domain ◽  
Plenum Chamber ◽  
Unidirectional Flow ◽  
Numerical Simulation Method ◽  
Airflow Distribution ◽  
Simulation Results

Uniformity of airflow distribution in a unidirectional flow cleanroom has been studied experimentally and numerically. The influence of the height of the plenum chamber and the velocity of airflow introduced into the chamber on the airflow uniformity are investigated experimentally. In addition, a numerical simulation method to predict airflow uniformity is proposed, taking into account the characteristics of the pressure loss of the filter. The calculation domain in this study includes not only the cleanroom but also the plenum chamber and the exhaust chamber. The validity of the numerical method is also verified by comparing the simulation results with the experiments. Finally, the numerical method is used to obtain an appropriate height for the plenum chamber.

scholarly journals Numerical simulation of cavitating two-phase gas-liquid three-dimensional flow in a duct of varying cross-section based on homogenous mixture model

2006 ◽  
Vol 28 (3) ◽  
pp. 134-144
Author(s):  
Nguyen The Duc
Keyword(s):  
Numerical Simulation ◽  
Numerical Method ◽  
Cross Section ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Grid Systems ◽  
Curvilinear Grid

The paper presents a numerical method to simulate two-phase turbulent cavitating flows in ducts of varying cross-section usually faced in engineering. The method is based on solution of two-phase Reynolds-averaged Navier-Stokes equations of two-phase mixture. The numerical method uses artificial compressibility algorithm extended to unsteady flows with dual-time technique. The discreted method employs an implicit, characteristic-based upwind differencing scheme in the curvilinear grid systems. Numerical simulation of an unsteady three-dimensional two-phase cavitating flow in a duct of varying cross-section with available experiment was performed. The unsteady important characteristics of the unsteady flow can be observed in results of numerical simulation. Comparison of predicted results with experimental data for time-averaged velocity and phase fraction are provided.

scholarly journals Quasi-Steady versus Navier–Stokes Solutions of Flapping Wing Aerodynamics

Fluids ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 81 ◽  
Author(s):  
Jeremy Pohly ◽  
James Salmon ◽  
James Bluman ◽  
Kabilan Nedunchezian ◽  
Chang-kwon Kang
Keyword(s):  
Stokes Equations ◽  
Aerodynamic Force ◽  
Lift Coefficient ◽  
Three Dimensional ◽  
Fruit Fly ◽  
Flapping Wing ◽  
Navier Stokes ◽  
Pitching Motion ◽  
Navier Stokes Equations ◽  
Wing Motion

Various tools have been developed to model the aerodynamics of flapping wings. In particular, quasi-steady models, which are considerably faster and easier to solve than the Navier–Stokes equations, are often utilized in the study of flight dynamics of flapping wing flyers. However, the accuracy of the quasi-steady models has not been properly documented. The objective of this study is to assess the accuracy of a quasi-steady model by comparing the resulting aerodynamic forces against three-dimensional (3D) Navier–Stokes solutions. The same wing motion is prescribed at a fruit fly scale. The pitching amplitude, axis, and duration are varied. Comparison of the aerodynamic force coefficients suggests that the quasi-steady model shows significant discrepancies under extreme pitching motions, i.e., the pitching motion is large, quick, and occurs about the leading or trailing edge. The differences are as large as 1.7 in the cycle-averaged lift coefficient. The quasi-steady model performs well when the kinematics are mild, i.e., the pitching motion is small, long, and occurs near the mid-chord with a small difference in the lift coefficient of 0.01. Our analysis suggests that the main source for the error is the inaccuracy of the rotational lift term and the inability to model the wing-wake interaction in the quasi-steady model.

Numerical Simulation on Flight Dynamic Characteristics of Elastic Wing Based on Gust Response

2013 ◽  
Vol 397-400 ◽  
pp. 378-383
Author(s):  
Wen Hui Dong ◽  
Chun Lei Yang ◽  
Yan Hui Li ◽  
Hong Guang Jia
Keyword(s):  
Numerical Simulation ◽  
Numerical Method ◽  
Stokes Equations ◽  
Fluid Dynamic ◽  
Navier Stokes ◽  
Dynamic Problems ◽  
Aerodynamic Forces ◽  
Structural Dynamic ◽  
Navier Stokes Equations ◽  
Gust Response

In this paper, the numerical method was developed to flight dynamics characteristics of elastic wing under the action of the discrete gust. In this numerical method, the aerodynamic forces of the elastic wing were calculated by solving the unsteady Navier Stokes equations, and incorporating the grid velocity method to simulating the gust response of the typical NACA0006 airfoil to the step changes in the angle of attack of aircraft . it is shown in results that the calculated lift responses of the airfoil agree well with both the exact theoretical value and calculated value in reference. the elastic effect was considered with RayleighRitz method, so that the fluid dynamic,structural dynamic and flight dynamic problems can be coupled to solve. and AGARD445.6 elastic wing for the numerical simulation of the flight characteristics.

scholarly journals Numerical Simulation Study on the Effects of Course Keeping on the Roll Stability of Submarine Emergency Rising

2019 ◽  
Vol 9 (16) ◽  
pp. 3285 ◽  
Author(s):  
Shudi Zhang ◽  
Hongwei Li ◽  
Tiedong Zhang ◽  
Yongjie Pang ◽  
Qinglong Chen
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Coupling Effect ◽  
Incidence Angle ◽  
Simulation Method ◽  
Numerical Prediction ◽  
Navier Stokes ◽  
Root Cause ◽  
Numerical Simulation Method ◽  
Yaw Angle

A direct numerical simulation method based on Reynolds Average Navier–Stokes (RANS) equations is used to carry out numerical prediction studies of submarine emergency rising in this paper. Firstly, a numerical simulation of the nonpropelled model without rudder manipulating is accomplished as the basis of this study. The numerical prediction results are in good agreement with the experimental data, which proves the feasibility and accuracy of the direct numerical simulation method. Meanwhile, both model tests and numerical simulation results reveal the strong coupling effect between roll and yaw motions during the underwater ascending process. Based on the above observation and analysis, another two numerical simulations, whose grids are identical with the non-manipulation simulation, are conducted respectively under the condition of rudder steering, i.e., course keeping simulation and self-propulsion simulation. An optimized S surface controller based on conditional determination is designed to manipulate the rudders. As a result, the yaw angle of the latter two simulations is limited within the range of 0.2° and 0.8° respectively, proving the effectiveness of the S surface controller. Correspondingly, the maximum roll angle is reduced by 96% and 70% respectively, which demonstrates that the roll stability is significantly enhanced by improving the course keeping ability of the model. Moreover, it is also proven from the perspective of reverse verification that, the excessive yaw deviation is the root cause of emergency rising roll instability for the situation of incidence angle lower than 30°.

scholarly journals MATHEMATICAL MODELING OF THE TRANSPORT OF OIL AND OIL PRODUCTS ON THE WATER SURFACE

2021 ◽  
Vol 73 (1) ◽  
pp. 14-22
Author(s):  
А. Issakhov ◽  
◽  
K. Iskendir ◽  
Keyword(s):  
Numerical Method ◽  
Water Surface ◽  
River Flow ◽  
Stokes Equations ◽  
Oil Pollution ◽  
Calculated Data ◽  
Simulation Method ◽  
Navier Stokes ◽  
The Caspian Sea ◽  
Volga River

Oil pollution on the water surface is one of the most dangerous and difficult-to-eliminate emergencies. This article shows the results of numerical modeling of oil transport on the surface of the Caspian Sea, taking into account the wind and the Volga River. The numerical method is based on the Navier Stokes equations, which describes the flow of an incompressible viscous fluid. The numerical method was verified using a test problem and the calculation results were compared with the calculated data of other authors. The aim of the study is to assess the possibility and efficiency of using the numerical simulation method to study the features of the formation of the composition of seawater after its mixing with oil and its subsequent distribution. The behavior of an oil slick at different speeds of river flow and oil spill is shown; it was also tested with and without wind in these cases. The calculated values obtained can make it possible to predict in the future the most accurate data on the spread of oil pollution in order to prevent an environmental threat.

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