# Thermo-Osmosis in a one-dimensional column

This benchmark is available as a Jupyter notebook: Notebooks/thermo-osmosis.run-skip.ipynb.

## Problem description

The problem describes a one-dimensional column at $$T$$=300 K in sudden contact with a temperature reservoir at one side at $$T_1$$ = 350 K.

Thermo-osmotic and filtration effects are described by contributions to the hydraulic flux $$J^w$$ $$J^w=-\rho_w \frac{\mathbf{k}}{\mu}\left(\nabla p-\rho_w \mathbf{g} \right)-\rho_w \mathbf{k}_{pT} \nabla T,$$ and the conductive heat flux $$I$$ I=- \mathbf{\lambda}_s (1-\phi)+\mathbf{\lambda}w \phi)- \mathbf{k}{Tp} \nabla p,

where $$\mathbf{k}_{pT}$$ is the phenomenological coefficient of thermo-osmosis and $$\mathbf{k}_{Tp}$$ the phenomenological coefficient of thermo-filtration. It can be shown that $$\mathbf{k}_{Tp}=T*\mathbf{k}_{pT}$$ (Zhou et al. 1998).

## Get benchmark results

import os
import vtuIO
import numpy as np

filename = "expected_Column_ts_68_t_7200000.000000.vtu"
data_dir = os.environ.get('OGS_DATA_DIR', '../../Data')
file = {}
file["THM"] = f"{data_dir}/ThermoHydroMechanics/Linear/ThermoOsmosis/{filename}"
file["TR"] = f"{data_dir}/ThermoRichardsFlow/ThermoOsmosis/{filename}"
file["TRM"] = f"{data_dir}/ThermoRichardsMechanics/ThermoOsmosis/{filename}"
x=np.array([i*0.1 for i in range(200)])
r = np.array([[i,0.5,0.0] for i in x])
resp = {}
respvars = ["temperature", "pressure"]
for model in file:
resp[model] = {}
f = vtuIO.VTUIO(file[model], nneighbors=100, dim=2)
for var in respvars:
if "M" in model:
resp[model][var] = f.get_set_data(f"{var}_interpolated",pointsetarray=r)
else:
resp[model][var] = f.get_set_data(f"{var}",pointsetarray=r)

/home/buchwalj/.local/lib/python3.10/site-packages/vtuIO.py:147: PerformanceWarning: DataFrame is highly fragmented.  This is usually the result of calling frame.insert many times, which has poor performance.  Consider joining all columns at once using pd.concat(axis=1) instead.  To get a de-fragmented frame, use newframe = frame.copy()
df["r_"+str(i)] = (df[x]-val[x]) * (df[x]-val[x]) + (df[y]-val[y]) * (df[y]-val[y])


An analytical solution was provided by Zhou et al. 1998 and can be obtained via github. For this example we used $$\mathbf{k}_{pT}=2.7e-10\, m^2/(s K)$$ and a fully saturated material. More details on model parameters can be found in the corresponding project files. The Thermo-Richards (TR) model uses a correction to account for mechanical effects in the mass-balance equation. See Buchwald et al. 2021 for further details.

import zhou_solution_thermo_osmosis
aTO = zhou_solution_thermo_osmosis.ANASOL(0,50,100)
aNoTO = zhou_solution_thermo_osmosis.ANASOL(0,50,100)
aNoTO.Sw = 0
t=7.2e6


## Plot temperature and pressure along the column

import matplotlib.pyplot as plt
plt.rcParams['figure.figsize'] = (12, 10)
plt.rcParams['font.size'] =  22
marker = ['|', '+', 'x']

for i, model in enumerate(resp):
plt.plot(x,resp[model]["temperature"], marker[i], label=model)
plt.plot(x,(aTO.T(x,t,10)+300), label="analytical solution")
plt.plot(x,(aNoTO.T(x,t,10)+300), label="analytical solution no thermo-osmosis")
plt.xlabel("$x$ / m")
plt.xlim([0,20])
plt.ylabel("$T$ / K")
plt.legend()
plt.title("temperature");


for i, model in enumerate(resp):
plt.plot(x,resp[model]["pressure"], marker[i], label=model)
plt.plot(x,(aTO.p(x,t,10)), label="analytical solution")
plt.plot(x,(aNoTO.p(x,t,10)), label="analytical solution, no thermo-osmosis")
plt.xlabel("$x$ / m")
plt.ylabel("$p$ / Pa")
plt.xlim([0,20])
plt.legend()
plt.title("pressure");


## Diffference between analytical and the numerical solution:

for i, model in enumerate(resp):
plt.plot(x,(resp[model]["temperature"]-(aTO.T(x,t,10)+300)), marker[i], label=model)
plt.xlabel("$x$ / m")
plt.xlim([0,20])
plt.ylabel("$\Delta T$ / K")
plt.legend()
plt.title("temperature");


for i, model in enumerate(resp):
plt.plot(x,resp[model]["pressure"]-aTO.p(x,t,200), marker[i], label=model)
plt.xlabel("$x$ / m")
plt.ylabel("$\Delta p$ / Pa")
plt.xlim([0,20])
plt.legend()
plt.title("pressure");


The differences between the analytical solution and OGS is assumed to come from the neglectance of the advective heat-flux in the analytical solution.

## References

[1] Zhou, Y., Rajapakse, R. K. N. D., & Graham, J. (1998). A coupled thermoporoelastic model with thermo-osmosis and thermal-filtration, International Journal of Solids and Structures, 35(34-35), 4659-4683.

[2] Buchwald, J., Kaiser, S., Kolditz, O., & Nagel, T. (2021). Improved predictions of thermal fluid pressurization in hydro-thermal models based on consistent incorporation of thermo-mechanical effects in anisotropic porous media. International Journal of Heat and Mass Transfer, 172, 121127.

This article was written by Jörg Buchwald. If you are missing something or you find an error please let us know. Generated with Hugo 0.96.0. Last revision: May 27, 2022