Page 183 - DCAP601_SIMULATION_AND_MODELING

Unit 10: Simulation of a PERT Network (II)

Generic examples of types of computer simulations in science, which are derived from an Notes
underlying mathematical description:
1. A numerical simulation of differential equations which cannot be solved analytically,
theories which involve continuous systems such as phenomena in physical cosmology,
fluid dynamics (e.g. climate models, roadway noise models, roadway air dispersion
models), continuum mechanics and chemical kinetics fall into this category.
2. A stochastic simulation, typically used for discrete systems where events occur
probabilistically, and which cannot be described directly with differential equations (this
is a discrete simulation in the above sense). Phenomena in this category include genetic
drift, biochemical or gene regulatory networks with small numbers of molecules.
Specific examples of computer simulations follow:
1. Statistical simulations based upon an agglomeration of a large number of input profiles,
such as the forecasting of equilibrium temperature of receiving waters, allowing the
gamut of meteorological data to be input for a specific locale. This technique was developed
for thermal pollution forecasting .

2. Agent based simulation has been used effectively in ecology, where it is often called
individual based modeling and has been used in situations for which individual variability in
the agents cannot be neglected, such as population dynamics of salmon and trout (most
purely mathematical models assume all trout behave identically).

3. Time stepped dynamic model. In hydrology there are several such hydrology transport
models such as the SWMM and DSSAM Models developed by the U.S. Environmental
Protection Agency for river water quality forecasting.

4. Computer simulations have also been used to formally model theories of human cognition
and performance, e.g. ACT-R
7. Computer simulation using molecular modeling for drug discovery

8. Computer simulation for studying the selective sensitivity of bonds by mechanochemistry
during grinding of organic molecules.
9. Computational fluid dynamics simulations are used to simulate the behaviour of flowing
air, water and other fluids. There are one-, two- and three- dimensional models used. A
one dimensional model might simulate the effects of water hammer in a pipe. A
two-dimensional model might be used to simulate the drag forces on the cross-section of
an aeroplane wing. A three-dimensional simulation might estimate the heating and cooling
requirements of a large building.
10. An understanding of statistical thermodynamic molecular theory is fundamental to the
appreciation of molecular solutions. Development of the Potential Distribution Theorem
(PDT) allows one to simplify this complex subject to down-to-earth presentations of
molecular theory.

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