"""Computation of friction drag."""
# This file is part of FAST-OAD : A framework for rapid Overall Aircraft Design
# Copyright (C) 2021 ONERA & ISAE-SUPAERO
# FAST 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 <https://www.gnu.org/licenses/>.
import numpy as np
[docs]def get_flat_plate_friction_drag_coefficient(length, mach, reynolds):
"""
:param length: flat plate length in meters
:param mach: Mach number
:param reynolds: Reynolds number
:return: Drag coefficient w.r.t. a surface of area length*1 m**2
"""
c_f = 0.455 / ((1 + 0.144 * mach ** 2) ** 0.65 * (np.log10(reynolds * length)) ** 2.58)
return c_f