COMPUTATIONAL STUDY OF TURBULENT FLOW OVER A SPHERE

INTRODUCTION

Computational Fluid Dynamics or CFD is the analysis of systems involving fluid flow, heat transfer and associated phenomena such as chemical reactions by means of computer-based simulation.
It is becoming very popular to solve flow problems without doing any experiment. We can assume practical situation of any flow system without go through the experiment. So it is very economical.

WHY USED CFD?

Analysis and Design
1. Simulation-based design instead of “build & test”
More cost effective and more rapid than EFD
CFD provides high-fidelity database for diagnosing flow field
2. Simulation of physical fluid phenomena that are difficult for experiments
Full scale simulations (e.g., ships and airplanes)
Environmental effects (wind, weather, etc.)
Hazards (e.g., explosions, radiation, pollution)
Physics (e.g., planetary boundary layer, stellar evolution)
Knowledge and exploration of flow physics

APPLICATION OF CFD

1.Aerospace
2.Automotive
3,Biomedical
4.Chemical processing
5.Heat ventilation air condition
6.Hydraulics
7.Power generation
8.Sports
9.Marine etc.

OBJECTIVES
My objectives are to know and analyze the followings:
To know about the basics of fluid dynamics.
To know about the computational fluid dynamics (CFD).
To know the application of CFD.
To know about the point of separation for the turbulent flow over a sphere.
To know about the effect of diameter on the point of separation.
To know about the effect of velocity on the point of separation.
To know about the effect of diameter on the pressure co-efficient.
To know about the effect of velocity on the pressure co-efficient.
To know about the effect of diameter on the skin friction co-efficient..
To know about the effect velocity on the skin friction co-efficient.

CONCLUSION

We choose spherical co-ordinate system(r, θ, ϕ) for the analysis.
Around 680 iterative steps needed for the convergence.
For finding pressure co-efficient and skin friction co-efficient at different angle the range is chosen from 0 radian to π radian.
The velocity vector represents both direction and magnitude of the flow .
Flow separation occurs earlier in case of larger diameter of the sphere.
For higher velocity separation starts early than lower velocity.