This thesis derives a first approximation model that will describe the flow of fluid in microfluidic devices such as in microchannels, microdiffusers and micronozzles using electrical network modelling. The important parameter that is of concern is the flow rates of these devices. The purpose of this work is to contribute to the physical component of our interactive Virtual Reality (VR)-prototyping tool for MEMS, with emphasis on fast calculations for interactive CAD design. Current calculations are too time consuming and not suitable for interactive CAD with dynamic animations. This work contributes to and fills the need for the development of MEMS dynamic visualisation, showing the movement of fluid within microdevices in time scale. Microfluidic MEMS devices are used in a wide range of applications, such as in chemical analysis, gene expression analysis, electronic cooling system and inkjet printers. Their success lies in their microdimensions, enabling the creation of systems that are considerably minute yet can contain many complex subsystems. With this reduction in size, the advantages of requiring less material for analysis, less power consumption, less wastage and an increase in portability becomes their selling point. Market size is in excess of US$50 billion in 2004, according to a study made by Nexus. New applications are constantly being developed leading to creation of new devices, such as the DNA and the protein chip. Applications are found in pharmaceuticals, diagnostic, biotechnology and the food industry. An example is the outcome of the mapping and sequencing of the human genome DNA in the late 1990's leading to greater understanding of our genetic makeup. Armed with this knowledge, doctors will be able to treat diseases that were deemed untreatable before, such as diabetes or cancer. Among the tools with which that can be achieved include the DNA chip which is used to analyse an individual's genetic makeup and the Gene chip used in the study of cancer. With this burgeoning influx of new devices and an increase in demand for them there is a need for better and more efficient designs. The MEMS design process is time consuming and costly. Many calculations rely on Finite Element Analysis, which has slow and time consuming algorithms, that make interactive CAD unworkable. This is because the iterative algorithms for calculating the animated images showing the ongoing proccess as they occur, are too slow. Faster computers do not solve the void of efficient algorithms, because with faster computer also comes the demand for a fasters response. A 40 - 90 minute FEA calculation will not be replaced by a faster computer in the next decades to an almost instant response. Efficient design tools are required to shorten this process. These interactive CAD tools need to be able to give quick yet accurate results. Current CAD tools involve time consuming numerical analysis technique which requires hours of numerous iterations for the device structure design followed by more calculations to achieve the required output specification. Although there is a need for a detailed analysis, especially in solving for a particular aspect of the design, having a tool to quickly get a first approximation will greatly shorten the guesswork involved in determining the overall requirement. The underlying theory for the fluid flow model is based on traditional continuum theory and the Navier-Stokes equation is used in the derivation of a layered flow model in which the flow region is segmented into layered sections, each having different flow rates. The flow characteristics of each sections are modeled as electrical components in an electrical circuit. Matlab 6.5 (MatlabTM) is used for the modelling aspect and Simulink is used for the simulation.

Across industries, Computer-aided design (CAD) programs are used to create vehicle parts. Simultaneously, virtual reality (VR) has become more common. Can these two co-existing technologies benefit one another? This thesis investigates how CAD modeling can be enhanced with the help of VR. Specifically, it focuses on importing CAD models during the runtime of a VR application, visualizing those models in real size. An additional feature includes the ability to interact with the imported CAD models, enabling assembly simulations. This thesis specifically explores how parts of electric autonomous trucks can be assembled in VR.  The results are moderately satisfying, with users expressing both satisfaction and dissatisfaction with certain aspects of VR as a tool in this context. However, only two users evaluated the application, indicating the need for a more extensive evaluation. / I flera industrier är CAD-program vanliga för att modellera delar till fordon. Samtidigt växer virtual reality (VR) fram och blir allt vanligare. Kan dessa två teknologier samexistera och dra nytta av varandra? Det här arbetet undersöker om CAD-modellering kan dra fördel av VR som ett verktyg för visualisering. En av de mer unika aspekterna av detta arbete är hur import av CAD-modeller under körtid  hanteras. En annan funktionalitet som undersöks är möjligheten att interagera med de importerade CAD-modellerna, vilket också öppnar för möjligheter att simulera monteringsprocesser. Resultatet var någorlunda tillfredsställande enligt intressenterna som utvärderade den slutgiltiga VR-applikationen. Det fanns aspekter som inte var helt tillfredsställande samtidigt som det fanns delar som var bra. Det ska beaktas att det endast var två intressenter som utvärderade den slutgiltiga applikationen, vilket indikerar att det behövs mer utvärdering för att fastställa ett gediget resultat.