Summary

This project provides a python library to model the viscous effects for thin boundary layers using the integral boundary layer method. Check out the documentation for more info.

Example Usage

Currently there are a few concrete models to use. One is Thwaites' method [Thwaites1949], which is a single equation model for laminar boundary layers. Given an edge velocity distribution, u_e, points along the boundary layer edge, s, and initial momentum thickness, delta_m0, the class will calculate the boundary layer properties. These properties can then be queried at any point along the body. For example:

from ibl.thwaites_method import ThwaitesMethodNonlinear

# Configure edge information
u_e = ...  # edge velocity profile
s = ...  # arc-length distance from stagnation point
rho_inf = ...  # reference density
nu_inf = ...  # reference kinematic viscosity

# Calculate the initial coditions
delta_m0 = ...  # initial momentum thickness

# Construct IBL model
tm = ThwaitesMethodNonlinear(U_e=u_e)
tm.initial_delta_m = delta_m0
rtn = tm.solve(x0=s[0], x_end=s[-1])

# Obtain results
if not rtn.success:
    print("Could not get solution for Thwaites method: " + rtn.message)
else
    tau_wall = tm.tau_w(s, rho_inf)

Similarly for a turbulent boundary layer, Head's method [Head1958] can be used to calculate the properties for a turbulent boundary layer. In addition to the initial momentum thickness, the initial displacement shape factor, shape_d0, is needed to initialize the model. Otherwise, the interface is the same as for Thwaites' method:

from ibl.head_method import HeadMethod

# Configure edge information
u_e = ...  # edge velocity profile
s = ...  # arc-length distance from stagnation point
rho_inf = ...  # reference density
nu_inf = ...  # reference kinematic viscosity

# Calculate the initial coditions
delta_m0 = ...  # initial momentum thickness
shape_d0 = ...  # initial displacement shape factor

# Construct IBL model
hm = HeadMethodNonlinear(U_e=U_e)
hm.initial_delta_m = delta_m0
hm.initial_shape_d = shape_d0
rtn = hm.solve(x0=s[0], x_end=s[-1])

# Obtain results
if not rtn.success:
    print("Could not get solution for Head method: " + rtn.message)
else
    tau_wall = hm.tau_w(s, rho_inf)

[Thwaites1949]

Thwaites, B. “Approximate Calculation of the Laminar Boundary Layer.” The Aeronautical Journal, Vol. 1, No. 3, 1949, pp. 245–280.

[Head1958]

Head, M. R. Entrainment in the Turbulent Boundary Layer. Publication 3152. Ministry of Aviation, Aeronautical Research Council, 1958.

Contributors

The main contributors to this project are:

• David D. Marshall
• Malachi Edland (original implementation of Thwaites’ Method, Head’s Method, and Michel transition criteria).

Version History

• 0.5.6 - Refactored reference data and analytic results classes and updated tests
• 0.5.5 - Improved project infrastructure
• 0.5.4 - Minor documentation updates
• 0.5.3 - Fixed documentation to display on GitHub
• 0.5.0 - Updated interface to IBL methods to simplify configuration and provided more features that can be obtained from the IBL methods. Added documentation and cleaned up the code.
• 0.0.3 - Last release directly supporting Malachi’s thesis
• 0.0.2 - Code is mostly working as from Malachi’s thesis
• 0.0.1 - Initial Release

License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.