3
Time required to the level of fluid in a tank
??????= ?
�=2 � ℎ
ℎ2
�
�
ℎ1
�=2 � ℎ
5
Forces on a Fluid Particle (Control Volume)
Surface Forces : Forces results from the interaction between
the control volume and the surroundings.
1. Pressure Force
2. Viscous Force
Body Forces : Forces associated with the volume of the control
volume.
1. Gravity Force (Weight)
2. Electromagnetic force (when the control volume is
subjected to electric or magnetic fields)
15
Energy equation
From the first law of thermodynamics,
�
d�
d�
= ∆�+∆�
Rate of work doneon a fluid particle
is equal to the product of the force
and the velocity component in the
direction of the forceNet rate of heat transfer to
the fluid particle
Energy of the fluid is the sum of
1.Internal energy
2.Kinetic energy
3.Potential energy
16
Energy equation
Viscous dissipation , results from the work
added to the control volume due to the
viscous force
Source term
+??????
�
@Osama Abdelrehim - Mohamed Sameh 17
18
1D Heat Conduction
Assumptions:
•Steady heat transfer
•No heat generation
•1-D heat flow (T=T(x))
Required:
1.Apply the assumptions to write down the heat transfer equation
2.Integrate the equation apply boundary conditions to find a
formula of the temperature in x-direction if the temperature at
the beginning of the rod = T
1, and at the end = T
2