We were discussing the basics of Boundary
layer theory, laminar
boundary layer, turbulent
boundary layer, boundary
layer thickness, displacement thickness and momentum thickness, energy thickness and drag force &lift force, in the subject of fluid mechanics, in our recent posts.
After understanding the fundamentals of drag and lift force, we will see now drag and lift coefficient, with the help of this
post.
We have already discussed that drag and lift forces
will be dependent over the various factors such as density of the fluid,
upstream velocity, size, shape and orientation of the body. It will be quite easy
to work with appropriate dimensionless numbers.
These dimensionless numbers will represent the drag
and lift characteristics of the body and these dimensionless numbers will be
termed as drag coefficient and lift coefficient.
Drag coefficient
Drag coefficient is basically defined as the ratio
of drag force to the dynamic pressure. Drag coefficient could be determined with
the help of following equation as mentioned here. Drag coefficient will be
represented by CD.
Lift coefficient
Lift coefficient is basically defined as the ratio
of lift force to the dynamic pressure. Lift coefficient could be determined with
the help of following equation as mentioned here. Lift coefficient will be
represented by CL.
Where,
½ ρV2 = Dynamic pressure
CD =
Co-efficient of drag
CL =
Co-efficient of lift
A = Area of the body which is projected area of the
body perpendicular to the direction of flow
FR = Resultant force on the
body
ρ = Density of the fluid
V = Flow velocity relative to the object
Further we will go ahead to start a new topic i.e.continuity equation for compressible fluid flow,
in the subject of fluid mechanics, with the help of our next post.
Do you have any suggestions? Please write in comment
box.
Reference:
Fluid mechanics, By R. K. Bansal
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