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1

The use of solution adaptive grid for low Reynolds number flows

Kaennakham S., Russell M., Holdo A. E.

International Journal of Applied Mechanics and Engineering

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2008

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Vol. 13, no 1

123-143

EN

The present work demonstrates the application of solution adaptive grids to three low Reynolds number cases, flow in a circular pipe, flow in a channel with a sudden expansion and flow in a lid-driven cavity. A number of refinement variabies are selected and comparisons are made between the results of the differing refinement variabies. The results from the test cases are compared with experimental as well as computational results from fixed grid cases. The use of solution adaptive grid is seen to yield good results when compared with experimental values, and computing time is seen to be reduced compared with fixed grid computations.

2

Industrial applications of computational fluid dynamics

Holdo A. E.

International Journal of Applied Mechanics and Engineering

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2002

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Vol. 7, no 1

85-105

EN

Computational Fluid Dynamics (CFD) has increased in usage within many areas of industry. In a large number of cases CFD is seen as an extension of CAD or FEM modelling and a long term vision is the integration of CFD with CAD and FEM structural analysis. Because of this it is now commonplace to import CAD based solid models into CFD packages for the use of studies. This is in principle a very practical approach as it saves model generation time. However, with such model generation there are many concerns such as the correct mesh density at the correct locations and the representation of curvature. The CAD model may appear smooth and be constructed by polynomials, but the resulting mesh may not be as smooth particularly if a Cartesian mesh or a mesh with lower order polynomials are used by the CFD solver. Alternative meshing strategies such as non-structured and structured meshes are also shown and results are discussed with reference to the integration of CAD with CFD. Another important issue for the industrial application of CFD is turbulence modelling. A comparison in terms of results and computing time between Reynolds Averaged Navier Stokes (RANS) modelling and Large Eddy Simulation (LES) is also given and finally it is suggested that meshing may be best taken care of by using solution adaptive meshes both for the prediction of main flow features as well as turbulence modelling.

3

A simple trajectory model for the near and far field of a jet in a cross flow

Toften T. H., Holdo A. E., Bullen P. R.

Applied Mechanics and Engineering

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2000

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Vol. 5, no 2

471-483

EN

Even with the present day extensive use of Computational Fluid Dynamics (CFD), simplified analytical expressions for Fluid Dynamic phenomena have their applications in highlighting significant mechanisms and aiding initial engineering estimates. The present work shows that experimental data for the trajectory of the centre line of jets exposed to a cross-flow can be found from a single expression. The expression is derived from first principles and unlike most other power law formulas the exponents are not empirically determined from measurements. In comparison with other single expressions based on dimensional analysis, which results in differing expressions for differing parts of the flow field, the equation presented here combines the asymptotic assumptions into a single expression.

4

The influence of inlet boundary conditions on the near field of a plane turbulent jet

Simpson B. A. F., Holdo A. E.

Applied Mechanics and Engineering

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1999

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Vol. 4, no 4

817-821

EN

Numerical investigations into the sensitivity of the near field of a plane jet to the inlet boundary conditions were performed, employing both finite element and finite volume methods together with the k-'epsilon' turbulence model. The study shows that the near field is insensitive to the turbulent inlet boundary conditions when a uniform velocity profile is used. However, when a non-uniform, shear dominated velocity profile is used, the assignment of turbulent parameters has a substantial effect on the solution.