[PhD Thesis Presentation] - Chola Kalale - Development of an SPH variant of implicit LES for studying wave energy transport

Development of an SPH variant of implicit LES for studying wave energy transport

Abstract:

The smoothed particle hydrodynamics (SPH) method is an efficient numerical technique for simulating complex problems such as free flows.  Since such flows are characterized by high Reynolds number,  turbulence modeling is a necessity.   In the literature,  some models from other numerical schemes have been adopted but comprehensive analyses of their effectiveness have not been provided.

In this thesis,  a version of SPH that implicitly models turbulence has been developed. First, using a convolution filter, a filtering transform (FIT) is proposed and applied to the underlying, disordered field to construct a smooth field. Using the FIT, filtered equations consistent with explicit Large Eddy Simulation are derived.  Second, using a deconvolution filter, a de-filtering integral transform (DIT) is proposed as an inverse transform to the FIT. By applying the DIT to the filtered equations a version of SPH, to be called SPH−i is formulated.  In SPH−i, unlike SPH, the disordered field is evolved dynamically.  Third, unlike standard SPH two inverse filters are required; a convolution filter and a deconvolution filter.  A rigorous method for constructing these filters in 2D is presented.  Fourth,  to address the problem of numerical oscillations in the pressure field, common in standard SPH, has been addressed by introducing a differential equation to the pressure field that includes smoothing terms.

The proposed SPH−i, model was applied to a number of free surface flow problems and the results are encouraging.