scholarly journals Navier-Stokes Simulation of the MIT Flapping Foil Experiment Using an Unstructured Finite Volume Method

1999 ◽  
Author(s):  
Dong Jin Kang ◽  
Sang Soo Bae ◽  
Jae Won Kim
Keyword(s):  
Boundary Layer ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Local Minimum ◽  
Free Stream ◽  
Navier Stokes ◽  
Unsteady Boundary Layer ◽  
Flapping Foil ◽  
Volume Method ◽  
Unstructured Finite Volume Method

A Navier-Stokes simulation of the MIT flapping foil experiment is presented. The MIT experiment was designed to provide a good quality database for unsteady boundary layer flows. The unsteady boundary layer around a hydrofoil was generated by flapping two airfoils upstream of the hydrofoil. Present Navier-Stokes simulation is carried out on the entire experimental domain, including the flapping airfoils as well as the downstream fixed hydrofoil. Present Navier-Stokes code uses an unstructured finite volume method based on the SIMPLE algorithm. It uses QUICK scheme for the convective terms and the second order Euler backward differencing for time derivatives to keep second order accuracy spatially and temporally. All other spatial derivatives are approximated by using central difference scheme. All comparisons of present time averaged and unsteady solutions with the corresponding experimental data are satisfactory: all unsteady solutions are compared in terms of time mean and first harmonic. The first harmonic of the velocity shows a peak inside the boundary layer along the surfaces of the hydrofoil and has a local minimum near the edge of the boundary layer. The local minimum becomes manifest as the boundary layer grows. The unsteadiness in the free stream is transferred inside the boundary layer when an unsteady vortex impinges on the surface. The entrained unsteadiness travels with a local velocity slower than that in the free stream. This causes phase lag of the first harmonic between the free stream and the boundary layer and local minimum of the first harmonic near the edge of the boundary layer.

scholarly journals Simulation of free-surface flow in a tank using the Navier-Stokes model and unstructured finite volume method

2005 ◽  
Vol 219 (3) ◽  
pp. 251-266 ◽  
Author(s):  
X Zhang ◽  
N M Sudharsan ◽  
R Ajaykumar ◽  
K Kumar
Keyword(s):  
Free Surface ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Free Surface Flow ◽  
Offshore Structures ◽  
Surface Flow ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Volume Method ◽  
Unstructured Finite Volume Method

Modelling free-surface flow has very important applications in many engineering areas such as oil transportation and offshore structures. Current research focuses on the modelling of free surface flow in a tank by solving the Navier-Stokes equation. An unstructured finite volume method is used to discretize the governing equations. The free surface is tracked by dynamically adapting the mesh and making it always surface conforming. A mesh-smoothing scheme based on the spring analogy is also implemented to ensure mesh quality throughout the computaiton. Studies are performed on the sloshing response of a liquid in an elastic container subjected to various excitation frequencies. Further investigations are also carried out on the critical frequency that leads to large deformation of the tank walls. Another numerical simulation involves the free-surface flow past as submerged obstacle placed in the tank to show the flow separation and vortices. All these cases demonstrate the capability of this numerical method in modelling complicated practical problems.

A Hybrid Unstructured/Spectral Method for the Resolution of Navier-Stokes Equations

2009 ◽  
Author(s):  
Roque Corral ◽  
Javier Crespo
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Stokes Equations ◽  
High Order ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Navier Stokes Equations ◽  
The Third ◽  
Third Dimension ◽  
Volume Method

A novel high-order finite volume method for the resolution of the Navier-Stokes equations is presented. The approach combines a third order finite volume method in an unstructured two-dimensional grid, with a spectral approximation in the third dimension. The method is suitable for the resolution of complex two-dimensional geometries that require the third dimension to capture three-dimensional non-linear unsteady effects, such as those for instance present in linear cascades with separated bubbles. Its main advantage is the reduction in the computational cost, for a given accuracy, with respect standard finite volume methods due to the inexpensive high-order discretization that may be obtained in the third direction using fast Fourier transforms. The method has been applied to the resolution of transitional bubbles in flat plates with adverse pressure gradients and realistic two-dimensional airfoils.

A 3-D Finite Volume Method for Green Water Calculations

2005 ◽  
Author(s):  
Sheguang Zhang ◽  
Daniel Liut ◽  
Kenneth Weems ◽  
Woei-Min Lin
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Green Water ◽  
Navier Stokes ◽  
Alternating Direction ◽  
Implicit Solver ◽  
Hull Forms ◽  
Volume Method ◽  
Water Problems ◽  
Tank Sloshing

A 3-D Finite Volume method (FV3D) is developed and applied to green water problems. The Navier-Stokes (N-S) equations are discretized with the 3-D finite volume method on collocated Cartesian grids. The free surface motion is captured with the Volume of Fluid (VOF) method. The velocity and pressure fields are solved by the SIMPLER scheme with an alternating direction implicit solver. FV3D is validated against existing experimental and numerical results for tank sloshing and ship green-water-on-deck cases. This method is applicable to calculation of the green water effect on advanced wave-piercing hull forms.

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