What is Computer Simulation Technique?

ANSWER I: `Simulation' in general terms can be defined as the representation or imitation of a system in its realistic form. When a computer program is used to create a model to mimic a real world system, then the term `computer simulation' comes into action. Such models are called computer simulated models. Computer simulation is of two types. One is called discrete simulation, in which, a system is observed only at some fixed regular time points, an example of which is the queuing system. It is a system where the events or jobs arrive at a time and wait in the queue to be processed. Generally the queue operates in a FIFO (First In First Out) fashion. Some real time examples for this case can be customers waiting in the queue in banks or to buy groceries in departmental stores. The involvement of the computer here is to maintain the queue according to the arrival time of the event, in this case the customers, and process each event one after the other according to their arrival time.

The other type is called Analogue simulation, which involves traditional mathematics. This is applied to a system whose state varies continuously in time. In this technique, sets of differential equations were used to describe a system. Since computers have the ability to solve equations, using various algorithms, in minimal time, its usage was very much relevant here. Some examples of this type are cosmology systems and chemical applications, which involve a large number of equations and require huge computing power. 

ANSWER II: To simulate a phenomenon, on a computer, we need a mathematical model that imitates the phenomenon. As an example consider the motion of Earth around the sun. The sun and Earth attract each other.

Once we model this gravitational force we can simulate the elliptic orbit of Earth. Here we do not need a computer since the governing equation is simple.

But consider a projectile hurled in the atmosphere. Here the friction of air plays an important role. The trajectory can be stimulated by approximate numerical techniques. We start with the condition of the projectile (position and velocity; then frictional force is known) at some instant. We can calculate its condition after a very small interval.

Then the new value for friction can be evaluated. We continue this process of numerical integration to get the trajectory. Smaller the time interval employed more accurate is the solution. This is where the computer enters to make the job easy. Complex fluid flow phenomena like turbulent flows, vibration of an aeroplane frame, combustion, weather and ocean circulation are some of the examples that need huge computer power.