Existing Software Packages

Because of the mathematical and numerical difficulties involved in the development of a CFD package this activity has been undertaken mainly by specialists where the user is kept away from the details of the solution procedures. Nowadays there exist many user-friendly CFD packages which allow the engineer to set up and solve complex fluid flow problems with relative ease. First we would like to make a few comments on the selection of commercially available CFD packages and the aspects which should be kept in mind in this connection  

User requirements. Does the user merely want to use a CFD package in its existing form to study fluid flow and related phenomena or does the user intend to modify and further develop the physical models incorporated in this package For the second class of users it would be very beneficial to have access to the source code of the CFD package. In this last respect it is worrying that the claimed future trend is toward fewer and fewer CFD codes being available in source code. 

Dimensions. The number of relevant dimensions for the class of fluid flow problems to be studied should be identified. Although in many cases it will be necessary to solve the full three-dimensional transport equations it is often wise to first perform preliminary two-dimensional calculations in order to gain some computational experience for the system of interest. 

Preprocessing. Especially for analysis of fluid flow phenomena in complex geometries, the availability of efficient and easy-to-use preprocessors for both problem definition and grid generation is of crucial importance. Fortunately, most commercially available CFD packages meet this requirement. 

Numerical method. The choice of the proper numerical solution procedure should be left to specialists. Even when a particular CFD package has been chosen, the user can usually choose different solution strategies for the linearized equations (point or line relaxation techniques versus whole field solution techniques) and associated values of the relaxation parameters. The proper choice of relaxation factors to obtain converged solutions (at all) within reasonable CPU constraints is a matter of experience where cooperation between the engineer and the specialist is required. This is especially true for new classes of fluid flow problems where previous experience is nonexistent. 

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The existing software packages can be divided into two broad categories, namely, commercially available general-purpose codes such as PHOENICS,... 

Different computer programs use different parameter tables, and thus differ in their results. Nevertheless, most of the existing software packages for logP calculation arrive at satisfactory results. 

Additional features, which are provided by existing software packages besides parameter estimation, are numerical simulation and optimization. The first option gives an opportunity to calculate, for instance, reaction rates for conditions (temperature, pressures, concentrations, etc) at which no experiments were performed. 

Processing the data. This proves no problem with the aid of existing software packages. 

Ethylene is produced using ethane in a steam cracking furnace at 800°C. Assume that the reaction takes place in an isothermal conversion reactor where ethane single-pass conversion is 65%. Develop a process flow sheet for the production of ethylene from pure ethane. Use existing software package in your university to perform the material and energy balance of the entire process. 

ANNs are easier to be applied, especially using the existing software packages. 

There are numerous articles and references on computational research studies. If none exist for the task at hand, the researcher may have to guess which method to use based on its assumptions. It is then prudent to perform a short study to verify the method s accuracy before applying it to an unknown. When an expert predicts an error or best method without the benefit of prior related research, he or she should have a fair amount of knowledge about available options A savvy researcher must know the merits and drawbacks of various methods and software packages in order to make an informed choice. The bibliography at the end of this chapter lists sources for reviewing accuracy data. Appendix A of this book provides short reviews of many software packages. 

The modular design integrates, as far as possible, existing software from member states, to permit the free distribution of the package. Version 1.0 of PSAPACK was used in a IAEA international training course on PSA in safety decisions (1988). Since then, PSAPACK evolved in response to users requirements, and has been widely distributed. 

If there is no restriction placed on the proposal by having to use the current in-house computer system, the choices of hard ware/software packages are numerous. The software must be user friendly, complementary to existing systems to avoid duplication of asset registering, etc., and have the facility to expand (i.e. have other programs (modules) that enable greater use be made of the information held within the system). The program should also be compatible with any in-house computer system where possible. 

Crystallographic software comes in two categories, free software, and commercial software. In most cases, these software packages exist quite comfortably side by side and are often compatible with each other. There are advantages to each type of software, but as a member of the academic community and operating on a limited budget, my personal experience with commercial software is quite limited. 

Overall, most of the requirements for a process spectrometer/analyzer are straightforward to implement, but they do require attention at the design level. Another important area, which is FTIR specific, is the user interface and the need to provide for industry standard data communications. Standard software packages do exist for process instrumentation. For prototype development, and even for the front-end interface in a stand-alone mode of operation, software products, such as National Instraments Lab View and the Mathworks MatLab, are also important instrumentation development tools. Note that National Instruments also provides important computer-based electronics and hardware that meet most of the computer interfacing, and system control and communications needs for modem instrumentation. For practical installations, a product known... 

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