What is "preprocessor"

n. (context computing English) program that processes its input data to produce output that is used as input to another program

In computer science, a preprocessor is a program that processes its input data to produce output that is used as input to another program. The output is said to be a preprocessed form of the input data, which is often used by some subsequent programs like compilers. The amount and kind of processing done depends on the nature of the preprocessor; some preprocessors are only capable of performing relatively simple textual substitutions and macro expansions, while others have the power of full-fledged programming languages.

A common example from computer programming is the processing performed on source code before the next step of compilation. In some computer languages (e.g., C and PL/I) there is a phase of translation known as preprocessing.

In computer aided engineering (CAE) a preprocessor is a program which provides a graphical user interface (GUI) to define physical properties. This data is used by the subsequent computer simulation.

Steps that are followed in Pre-Processing

1> The geometry (physical bounds) of the problem is defined

2> The volume occupied by the fluid is divided into discrete cells (meshing)

3> The physical modeling is defined - Eg. equations of motion + enthalpy + radiation + species conservation

4> Boundary conditions are defined. This involves specifying the fluid behavior and properties at the boundaries of the problem. For transient problems, the initial conditions are also defined.

5> The simulation is started and the equations are solved iteratively as a steady state or transient

6> Finally a post-processor is used for the analysis and visualization of the resting solution

Category:Computer graphics