Computational modelling of multi-physics and multi-scale processes in parallel

This paper provides an overview of the developing needs for simulation software technologies for the computational modelling of problems that involve combinations of interactions amongst varying physical phenomena over a variety of time and space scales. Computational modelling of such problems requires software tech1nologies that enable the mathematical description of the interacting physical phenomena together with the solution of the resulting suites of equations in a numerically consistent and compatible manner. This functionality requires the structuring of simulation modules for specific physical phenomena so that the coupling can be effectively represented. These multi-physics and multi-scale computations are very compute intensive and the simulation software must operate effectively in parallel if it is to be used in this context. An approach to these classes of multi-disciplinary simulation in parallel is described, with some key examples of application to2 challenging engineering problems.

Multi-physics modelling for microelectronics and microsystems - current capabilities and future challenges

At present the vast majority of Computer-Aided- Engineering (CAE) analysis calculations for microelectronic and microsystems technologies are undertaken using software tools that focus on single aspects of the physics taking place. For example, the design engineer may use one code to predict the airflow and thermal behavior of an electronic package, then another code to predict the stress in solder joints, and then yet another code to predict electromagnetic radiation throughout the system. The reason for this focus of mesh-based codes on separate parts of the governing physics is essentially due to the numerical technologies used to solve the partial differential equations, combined with the subsequent heritage structure in the software codes. Using different software tools, that each requires model build and meshing, leads to a large investment in time, and hence cost, to undertake each of the simulations. During the last ten years there has been significant developments in the modelling community around multi- physics analysis. These developments are being followed by many of the code vendors who are now providing multi-physics capabilities in their software tools. This paper illustrates current capabilities of multi-physics technology and highlights some of the future challenges

Multi-physics modelling for the fabrication, packaging and reliability of micro-systems components

The latest advances in multi-physics modelling both using high fidelity techniques and reduced order and behavioural models will be discussed. Particular focus will be given to the application and validation of these techniques for modelling the fabrication, packaging and subsequent reliability of micro-systems based components. The paper will discuss results from a number of research projects with particular emphasis on the techniques being developed in a major UK Goverment funded project - 3D-MINTEGRATION (www.3d-mintegration.com).

Choosing the appropriate level of coupling in multi-physics modeling of metallurgical processes

A computational model for the interrelated phenomena in the process of vacuum arc remelting is analyzed and adjusted of optimal accuracy and computation time. The decision steps in this case study are offered as an example how the coupling in models of similar processes can be addressed. Results show dominance of the electromagnetic forces over buoyancy and inertia for the investigated process conditions.

Challenges in integrative approaches to modelling the marine ecosystems of the North Atlantic: Physics to fish and coasts to ocean

It has long been recognised that there are strong interactions and feedbacks between climate, upper ocean biogeochemistry and marine food webs, and also that food web structure and phytoplankton community distribution are important determinants of variability in carbon production and export from the euphotic zone. Numerical models provide a vital tool to explore these interactions, given their capability to investigate multiple connected components of the system and the sensitivity to multiple drivers, including potential future conditions. A major driver for ecosystem model development is the demand for quantitative tools to support ecosystem-based management initiatives. The purpose of this paper is to review approaches to the modelling of marine ecosystems with a focus on the North Atlantic Ocean and its adjacent shelf seas, and to highlight the challenges they face and suggest ways forward. We consider the state of the art in simulating oceans and shelf sea physics, planktonic and higher trophic level ecosystems, and look towards building an integrative approach with these existing tools. We note how the different approaches have evolved historically and that many of the previous obstacles to harmonisation may no longer be present. We illustrate this with examples from the on-going and planned modelling effort in the Integrative Modelling Work Package of the EURO-BASIN programme.

Arctic Oceanography - Oceanography: Atmosphere-Ocean Exchange, Biogeochemistry & Physics

The Arctic Ocean is, on average, the shallowest of Earth’s oceans. Its vast continental shelf areas, which account for approximately half of the Arctic Ocean’s total area, are heavily influenced by the surrounding land masses through river run-off and coastal erosion. As a main area of deep water formation, the Arctic is one of the main «engines» of global ocean circulation, due to large freshwater inputs, it is also strongly stratified. The Arctic Ocean’s complex oceanographic configuration is tightly linked to the atmosphere, the land, and the cryosphere. The physical dynamics not only drive important climate and global circulation patterns, but also control biogeochemical cycles and ecosystem dynamics. Current changes in Arctic sea-ice thickness and distribution, air and water temperatures, and water column stability are resulting in measurable shifts in the properties and functioning of the ocean and its ecosystems. The Arctic Ocean is forecast to shift to a seasonally ice-free ocean resulting in changes to physical, chemical, and biological processes. These include the exchange of gases across the atmosphere-ocean interface, the wind-driven ciruclation and mixing regimes, light and nutrient availability for primary production, food web dynamics, and export of material to the deep ocean. In anticipation of these changes, extending our knowledge of the present Arctic oceanography and these complex changes has never been more urgent.

Development of a technique to measure the residual strength of woodworm infested timber

This paper presents a study of the residual strength of Pinus sylvestris, which has been subject to attack by the furniture beetle (Anobium punctatum). It is relatively easy to stop the infestation, but difficult to assess the structural soundness of the remaining timber. Removal and replacement of affected structural elements is usually difficult and expensive, particularly in buildings of historic interest. Current on-site assessment procedures are limited. The main object of the study was to develop an on-site test of timber quality: a test which can be carried out on the surface and also at varying depths into the timber. It is based on a probe pull-out technique using a portable load-measuring device. Pull-out force values have been correlated with both strength and energy absorbed as measured by compression testing on laboratory samples of both sound and infested timber. These two relationships are significant and could be used to assess whether remedial work is needed. In addition, work on the use of artificial borings to simulate the natural worming of timber is presented and the findings discussed.

The 'Belfast' timber roof truss - is it sustainable and relevant today?

In the early 19th century the requirement for clear span industrial buildings brought about the development of a variety of timber truss types. The Belfast truss was introduced circa 1860 to meet the demand for efficient wide span industrial buildings. It has essentially a bow-string configuration with a curved top chord, straight horizontal bottom chord and close-spaced lattice web. Several thousand still exist in Ireland, many in buildings of historic significance. This paper sets out to demonstrate the efficiency of the Belfast truss and to show that, by modern structural design criteria, the concept, member sizes and joint details were well chosen. Trusses in historic buildings can be replicated almost exactly as originally fabricated. Results of a theoretical study are compared with the experimental behaviour of two full-scale trusses: one a replacement truss, tested in the laboratory; the other an 80-year-old truss tested on site. In addition, experimental results from a manufacturers archive material of full-scale truss tests carried out about 100 years ago are compared with theoretical models. As well as considering their significance in building conservation the paper proposes that Belfast trusses are an attractive sustainable alternative to other roof structures. The analysis, design, fabrication and testing of trusses have resulted in a better understanding of their behaviour which is not only of historic interest and fundamental to the repair/restoration of existing trusses, but also relevant to the design of modern timber trusses and the promotion of a sustainable form of roof construction.