Welcome to IBL’s documentation!

IBL is a Python library to model the viscous effects on surfaces using the integral boundary layer method. This method is intended for flows with relatively thin boundary layers that are attached. It takes an inviscid boundary layer edge velocity (in a variety of forms) along with some configuration settings and will calculate the corresponding wall shear stress, transpiration velocity, and other parameters based on the model used.

Note

This project is under development and the API might change between releases.

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.

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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/.

Contents:

Indices and tables