Abstract
Suddenly started laminar flow in the entrance region of a circular tube, with constant inlet velocity, is investigated analytically by using integral momentum approach. A closed form solution to the integral momentum equation is obtained by the method of characteristics to determine boundary layer thickness, entrance length, velocity profile, and pressure gradient.
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Abbreviations
- M(ξ, τ, η):
-
a function
- N(ξ, τ, η):
-
a function
- p :
-
pressure
- p*:
-
p/1/2ρU 2, dimensionless pressure
- Q(ξ, τ, η):
-
a function
- R :
-
radius of the tube
- r :
-
radial distance
- Re :
-
2RU/ν, Reynolds number
- t :
-
time
- U :
-
inlet velocity, constant for all time, uniform over the cross section
- u :
-
velocity in the boundary layer
- u*:
-
u/U, dimensionless velocity
- u 1 :
-
velocity in the inviscid core
- x :
-
axial distance
- y :
-
distance perpendicular to the axis of the tube
- y*:
-
y/R, dimensionless distance perpendicular to the axis
- δ :
-
boundary layer thickness
- δ*:
-
displacement thickness
- η :
-
δ/R, dimensionless boundary layer thickness
- θ :
-
momentum thickness
- μ :
-
absolute viscosity of the fluid
- ν :
-
μ/ρ, kinematic viscosity of the fluid
- ξ :
-
x/(R Re), dimensionless axial distance
- ρ :
-
density of the fluid
- τ :
-
tU/(R Re), dimensionless time
- τ w :
-
wall shear stress
References
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Lundgren, T. S., E. M. Sparrow and S. B. Starr, Trans. ASME 86 (1964) 620.
Schiller, L., Z. Angew. Math. Mech. 2 (1922) 96.
Schlichting, H., Boundary layer theory, 4th edition, McGraw-Hill, New York 1962.
Goldstein, S., Modern developments in fluid dynamics, 1st edition, Dover, New York 1965.
Atabek, H. B., Unsteady and oscillatory flows in the entrance regions of co-axial tubes, tubes, and channels, Ph. D. thesis, Un. of Minnesota, Minneapolis (Minn.), U.S.A. 1961.
Pearson, J. D., Numerical solution of the Navier-Stokes equations for the entrance region of suddenly accelerated parallel plates, Ph. D. thesis, Iowa State University of Science and Technology, Ames (Iowa), U.S.A. 1966.
Schuh, H., Z. Flugwissenschaften 5 (1953) 122.
Stewartson, K., Quart. J. Mech. Appl. Math. 4 (1951) 182.
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Avula, X.J.R. Analysis of suddenly started laminar flow in the entrance region of a circular tube. Appl. sci. Res. 21, 248–259 (1969). https://doi.org/10.1007/BF00411611
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DOI: https://doi.org/10.1007/BF00411611