David W. Holmes

A framework for parallel computational physics algorithms on multi-core: SPH in parallel

In this paper, a simulation framework that enables distributed numerical computing in multi-core shared-memory environments is presented. Using multiple threads allows a single memory image to be shared concurrently across cores but potentially introduces race conditions. Race conditions can be avoided by ensuring each core operates on an isolated memory block. This is usually achieved by running a different operating system process on each core, such as multiple MPI processes. However, we show that in many computational physics problems, memory isolation can also be enforced within a single process by leveraging spatial sub-division of the physical domain. A new spatial sub-division algorithm is presented that ensures threads operate on different memory blocks, allowing for in-place updates of state, with no message passing or creation of local variables during time stepping. Additionally, the developed framework controls task distribution dynamically ensuring an events based load balance. Results from fluid mechanics analysis using Smoothed Particle Hydrodynamics (SPH) are presented demonstrating linear performance with number of cores.

Parallel Computation Particle Methods for Multi-Phase Fluid Flow with Application Oil Reservoir Characterization

This contribution presents a strategy for programming mechanics simulations including particle methods on multi-core shared memory machines.

Mapping Nursing Pathways: A Diverse Modified Delphi Approach

Articulated education pathways between the vocational education training sector and universities provide opportunities for students wishing to progress to higher qualifications. Enrolled nurses seeking to advance their career in nursing can choose to enter baccalaureate degree programs through such alternative entry routes. Awarding of credit for prior studies is dependent on accurate assessment of the existing qualification against that which is sought. This study employed a modified Delphi method to inform the development of an evidence-based, structured approach to mapping the pathway from the nationally consistent training package of the Diploma of Nursing to the diversity of baccalaureate nursing programs across Australia. The findings of this study reflect the practical nature of the role of the enrolled nurse, particularly the greater emphasis placed on direct care activities as opposed to those related to professional development and the generation and use of evidence. These findings provide a valuable summative overview of the relationship between the Diploma of Nursing and the expectations of the registered nurse role.

Development of a competency mapping tool for undergraduate professional degree programmes, using mechanical engineering as a case study

ABSTRACT Mapping the curriculum of a professional degree to the associated competency standard ensures graduates have the competence to perform as professionals. Existing approaches to competence mapping vary greatly in depth, complexity, and effectiveness, and a standardised approach remains elusive. This paper describes a new mapping software tool that streamlines and standardises the competency mapping process. The available analytics facilitate ongoing programme review, management, and accreditation. The complete mapping and analysis of an Australian mechanical engineering degree programme is described as a case study. Each subject is mapped by evaluating the amount and depth of competence development present. Combining subject results then enables highly detailed programme level analysis. The mapping process is designed to be administratively light, with aspects of professional development embedded in the software. The effective competence mapping described in this paper enables quantification of learning within a professional degree programme, and provides a mechanism for holistic programme improvement.

Comparison of Semi-Implicit and Explicit Finite Difference Algorithms on Highly Parallel Processing Architectures

Modern GPUs (graphical processing units) are a common source of processing power inmany supercomputers. Their performance derives from the highly parallel architecture that is em-ployed and have the benefit of low cost, temperature and power consumption. Two finite differencemodels have been implemented on GPU, a semi-implicit and an explicit algorithm, to numericallymodel a stratified shear layer, that needs fine meshes to be modelled accurately. The GPU modelswere shown to improve performance by factors of around 50x and 20x for the semi-implicit and ex-plicit models respectively.

Comparison and Development of Equation of State Laws in Smoothed Particle Hydrodynamics

In this paper we present a brief comparison of existing equation of state laws used inSmoothed Particle Hydrodynamics (SPH) and introduce some new expressions for the equation ofstate for pressure, as well as to calculate temperature. In SPH literature practical examples of heatconduction and energy are scarce when compared with fluid flow formulations that determine pressuresimply from density and an artificial speed of sound. Such simplifications may be appropriate forisothermal flow problems; however, a more thermodynamically rigorous formulation is necessary forcomplex and thermally driven problems, particularly in geophysics. This work discusses conventionalequations of state, as well as presenting some new relations. This includes having pressure depend onthe energy of the system, and applying these relations to a number of proof of concept examplesdemonstrating natural convection and examining the parameters of the new equation of state. Thesedevelopments facilitate future work towards modelling more complex physical phenomena such asheat driven convective flow.

A Multigrid Accelerated Code for Simulating Unsteady Conjugate Natural Convection Boundary Layers

This paper presents a numerical study on the flow dynamics and heat transfer behaviour of unsteady conjugate natural convection boundary layers (CNCBLs) in a partitioned, air filled square cavity. An unsteady two-dimensional multigrid-assisted solver is developed in the C#.NET programming language on stretched Cartesian meshes. The finite volume method is used to discretise the governing equations. To solve the coupled pressure and velocity, the SIMPLE algorithm is used, and to increase simulation accuracy the Adam-Bashforth, QUICK and central difference schemes are employed for time, convection, and diffusion terms respectively. The Poisson pressure equation is solved through the use of the multigrid method. The developed code is used to model CNCBLs which typically require a large amount of simulation time. The numerical results provide detailed descriptions of unsteady CNCBLs and associated heat transfer behaviour over a wide range of Ra, such as the thermal and viscous boundary layer thicknesses, temperature and velocity distributions, and maximum velocities within the CNCBLs.

Characterizing Flow in Oil Reservoir Rock Using Smooth Particle Hydrodynamics

In this paper, a 3D Smooth Particle Hydrodynamics (SPH) simulator for modeling grain scale fluid flow in porous rock is presented. The versatility of the SPH method has driven its use in increasingly complex areas of flow analysis, including flows related to porous rock for both groundwater and petroleum reservoir research. Previous approaches to such problems using SPH have involved the use of idealized pore geometries (cylinder/sphere packs etc.). In this paper we discuss the characterization of flow in models with geometries acquired from 3D X‐ray microtomograph images of actual porous rock. One key advantage of SPH is realized when considering the complexity of multiple fluid phases (e.g., water and oil). By incorporating interfacial physics such as surface tension and wettability, it is possible to model the capillary behavior of multiple fluid phases with accuracy. Simulation results for permeability will be presented and compared to those from experimentation and other numerical methods showing good agreement and validating the method. By accurately reproducing the flow characteristics of actual porous rock samples, this work has made significant progress towards validating SPH for such applications.