Source code for dclab.features.emodulus_viscosity

#!/usr/bin/python
# -*- coding: utf-8 -*-
"""Viscosity computation for various media"""
from __future__ import division, print_function, unicode_literals

import numpy as np


[docs]def get_viscosity(medium="CellCarrier", channel_width=20.0, flow_rate=0.16, temperature=23.0): """Returns the viscosity for RT-DC-specific media Parameters ---------- medium: str The medium to compute the viscosity for. One of ["CellCarrier", "CellCarrier B", "water"]. channel_width: float The channel width in µm flow_rate: float Flow rate in µl/s temperature: float or ndarray Temperature in °C Returns ------- viscosity: float or ndarray Viscosity in mPa*s Notes ----- - CellCarrier and CellCarrier B media are optimized for RT-DC measurements. - Values for the viscosity of water are computed using equation (15) from :cite:`Kestin_1978`. """ if medium.lower() not in ["cellcarrier", "cellcarrier b", "water"]: raise ValueError("Invalid medium: {}".format(medium)) # convert flow_rate from µl/s to m³/s # convert channel_width from µm to m term1 = 1.1856 * 6 * flow_rate * 1e-9 / (channel_width * 1e-6)**3 * 2 / 3 if medium == "CellCarrier": temp_corr = (temperature / 23.2)**-0.866 term2 = 0.6771 / 0.5928 + 0.2121 / (0.5928 * 0.677) eta = 0.179 * (term1 * term2)**(0.677 - 1) * temp_corr * 1e3 elif medium == "CellCarrier B": temp_corr = (temperature / 23.6)**-0.866 term2 = 0.6771 / 0.5928 + 0.2121 / (0.5928 * 0.634) eta = 0.360 * (term1 * term2)**(0.634 - 1) * temp_corr * 1e3 elif medium == "water": # see equation (15) in Kestin et al, J. Phys. Chem. 7(3) 1978 if np.min(temperature) < 0 or np.max(temperature) > 40: msg = "For water, the temperature must be in [0, 40] degC! " \ "Got min/max values of '{}'.".format(np.min(temperature), np.max(temperature)) raise ValueError(msg) eta0 = 1.002 # [mPa] right = (20-temperature) / (temperature + 96) \ * (+ 1.2364 - 1.37e-3 * (20 - temperature) + 5.7e-6 * (20 - temperature)**2 ) eta = eta0 * 10**right return eta