With the development of technology for computers and the software that runs on them, programs which simulate processes have become more accessible and hence, applied to a greater number of applications. Most of the developments in mathematical simulations are in the automotive and aerospace industries. However, the use of these techniques in other industries is becoming more widespread with the advent of commercial software which can be run on a PC. Standard generic approaches have been developed which can be applied to a wide variety of problems.
Finite Element Analysis (FEA)
The main techniques can be differentiated by what they are trying to achieve. Finite Element Analysis (FEA) is used to perform structural solid engineering type problems. Examples of the use of this technique are:
• Crumple zones in cars during collisions
• Effectiveness of rubber seals on doors
• Plastic forming of sheet metals
Computational Fluid Dynamics (CFD)
While FEA has also been traditionally used to solve basic thermal problems, computational fluid dynamics (CFD) can be used for more complex problems. Such problems might involve very fluid or gaseous materials. Typical examples of the use of CFD include:
• Temperatures inside a boiler subject to turbulent gases
• Injection moulding of plastics
• Glass flow in melting tanks
As computing power increases still further, these techniques are moving closer together. For example forging and plastic extrusion are similar problems, but FEA deals with the stiffer material in forging, and CFD the less stiff plastic.
Application Specific Methods
Specific applications can be written for particular simulations. For example mass/heat transfer problems can be simplified without resorting to powerful FEA or CFD programs. An example of this is in the ceramics industry where it can be used to predict the temperatures and gas flows through a tunnel kiln (figure 1). These calculation would be based on variables such as flame gas, injection cooling, bypass gases, kiln lining and kiln cars. This modelling approach gives a fundamental understanding of the way in which the gas interacts with the rest of the kiln. As the application is specific the runtime is much quicker than FEA or CFD codes.
Figure 1. Schematic of a tunnel kiln (above) and temperature profile for a similar kiln (below).
Advantages of Computer Modelling
Modelling a process has the following benefits:
• Predictive rather than reactive approach to design
• More insight into a process
• Eliminate expensive and time consuming prototype development
• Confidence in radical design approaches
• Reduce manufacturing defects
• Shorten the time required to bring products to market