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Problem-1 of CFD Lab
Objective:To carry out CFD simulation
1. CFD simulation of laminar flow ofwater in a straight
horizontal pipe2. CFD simulation of turbulent flow ofwater in the
same pipe3. CFD simulation of laminar flow ofwater with a finer
mesh in the same pipeGeometry:Straight horizontal pipe
Diameter of pipe = 5 cm
Length of pipe = 100 cm
Orientation of pipe is such that the axis is in +y
direction.
problem-1.msh, the file containing the geometry and mesh will be
provided. problem-1-
finer.msh, the file containing the geometry and finer mesh will
also be provided.
Reynolds Number for Simulations
In the manual give to you the laminar flow has been simulated
for a mass flow rate =
0.027728 kg/sec and turbulent flow for mass flow rate = 0.27728
kg/s. In the lab you have to
carry out simulations
1. for laminar flow at Re = 1000 + (n-1)*50 where n = group
number
2. for turbulent flow at Re = 10*{1000+(n-1)*50} where n = group
number
Compute mass flow rate accordingly for simulations. For
turbulent flow take turbulent
intensity at inlet as 10% and length scale as 0.005 m.
The information given up to this point should not be a part of
you submission. The
report should be submitted in the format given below.
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Report for Problem-1 of CFD Lab Spring Semester Year 2010-11
1. Group Number:2.
Names of group members with roll numbers:
3. Date of submission:4. Results for simulation of laminar flow
with first mesh
Reynolds number =
Mass flow rate =
Axial velocity contours at inlet and outlet (show the contour
plots and discuss why they
are different for inlet and outlet)
Axial velocity profile (plot the axial velocity profile in the
middle of the pipe andcompare with theoretical velocity profile on
the same plot. Very briefly discuss the difference
and possible reasons for this difference)
Friction factor (calculate friction factor and compare with
theoretical value and very
briefly discuss the difference and possible reasons for the
same. Show the calculations)
5. Results of simulations for turbulent flow with first
meshReynolds number =
Mass flow rate =
Axial velocity profile (plot the axial velocity profile in the
middle of the pipe andcompare with theoretical velocity profile on
the same plot. Very briefly discuss the difference
and possible reasons for this difference. Theoretical velocity
profile for turbulent flow is
given in Annexure at the end of the format of this report)
Friction factor (calculate friction factor and compare with
theoretical value and very
briefly discuss the difference and possible reasons for the
same. Show the calculations)
Comparison of axial velocity profile with that for laminar flow
(normalize the axial
velocity profiles of laminar flow and turbulent flow using
average velocity for the two cases.
Plot the normalized profiles on the same graph and discuss the
difference)
Comparison of friction factor of laminar and turbulent flow
(discuss whether thevalues of friction factors for laminar flow and
turbulent flow are as one should have expected)
6. Results for laminar flow with finer meshAxial velocity
profile (plot the axial velocity profile for finer mesh along with
the axial
velocity profile for laminar flow with the previous mesh and
theoretical velocity profile and
very briefly discuss the difference)
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Friction factor (calculate friction factor for finer mesh and
compare with the frictionfactor for laminar flow with previous mesh
and discuss the results)
7. Conclusion (write very briefly what CFD simulations are able
to/ not able to predict)
Annexure
Theoretical velocity profile for turbulent flow
7
1
avgyR
r1V25.1V
=
where
A
QVavg =
Q is the flow rate, A is the cross-sectional area of pipe, R is
radius of the pipe, Vavg is the
average velocity through the pipe.
