Finding the accurate permittivity model for liquid water and heavy water at different temperatures in the Terahertz range

Author(s):  
Melanie Lavancier ◽  
Jean-Francois Lampin ◽  
Romain Peretti
2020 ◽  
Vol 35 ◽  
pp. 18-28
Author(s):  
Muhammad Rubayat Bin Shahadat ◽  
A.K.M.M. Morshed

Non-equilibrium molecular dynamics simulations have been employed to study the explosive boiling phenomena of water over a hot copper plate. The molecular system was comprised of three sections: solid copper wall, liquid water, and water vapor. A few layers of the liquid water were placed on the solid Cu surface. The rest of the simulation box was filled with water vapor. Initially, the water molecules were equilibrated by using Berendsen thermostat at 298 K. Then heat was given to the copper plate at different temperatures so that explosive boiling occurs. After achieving the equilibrium by performing the previous two steps, the liquid water at 298 K is suddenly dropped on the hot plate. NVE ensemble was used in the simulation and the temperature of the copper plate was controlled to different temperatures with phantom atom thermostat. Four temperatures (400K, 500K, 650 K and 1000K) were taken to study the explosive boiling. The simulation results show that, the explosive boiling temperature of water on Cu plate is 500 K temperature. At this point, the energy flux was found 1.79x108 J/m3 which is very promising with the experimental results. Moreover, if the temperature of the surface was increased the explosive boiling occurred at a faster rate. The simulation results also show that explosive boiling occurs earlier for the hydrophilic surface than hydrophobic surface as for the hydrophilic surface the water attracted the Cu plate more than the hydrophobic surface and so the amount of energy transfer is more for the hydrophilic surface.


2018 ◽  
Author(s):  
Katrin Lonitz ◽  
Alan J. Geer

Abstract. Permittivity models for microwave frequencies of liquid water below 0 °C (supercooled liquid water) are poorly constrained due to limited laboratory experiments and observations, especially for high microwave frequencies. This uncertainty translates directly into errors in retrieved liquid water paths of up to 80 %. This study investigates the effect of different liquid water permittivity models on simulated brightness temperatures by using the all-sky assimilation framework of the Integrated Forecast System. Here, a model configuration with an improved representation of supercooled liquid water has been used. The comparison of five different permittivity models with the current one shows a small mean reduction in simulated brightness temperatures of at most 0.15 K at 92 GHz on a global monthly scale. During austral winter differences occur more prominently in the storm tracks of the southern hemisphere and in the Intertropical Convergence Zone with values of around 0.5 K to 1.5 K. For most permittivity models the fit to observations is slightly improved compared to the default one. The permittivity model by Rosenkranz (2015) is recommended to be used inside the observation operator RTTOV-SCATT for frequencies below 183 GHz.


Author(s):  
Muhammad Rubayat Bin Shahadat ◽  
AKM M. Morshed ◽  
Amitav Tikadar ◽  
Titan C. Paul ◽  
Jamil A. Khan

Abstract Non-equilibrium Molecular Dynamics (NEMD) Simulation has been employed to investigate the nanobubble generation, growth and collapse in liquid water. The center molecules (240 water molecule) of the simulation domain were heated at five different temperatures (400K, 800K, 1500K, 2100K and 2800K) by velocity scaling for a very short period of time and the radius of the nano sized bubble was calculated. At 400K temperature, no nano bubble is formed but as temperature increases, nano bubble forms and the radius of the nano bubble increases. TIP-3P potential model has been used to predict the structural parameters of water molecules. The SHAKE algorithm has been employed to hold the bonds of O-H and H-O-H as rigid. The results obtained from the simulation were then compared with the results got from Rayleigh-Plesset Equation in order to show the discrepancy of MD simulation and the Hydrodynamic model. The simulation results indicate that Rayleigh-Plesset equation is not valid for prediction the formation, growth and collapse of nano bubble in liquid water because of its uncertainty in predicting the surface tension and ignoring the viscosity.


2013 ◽  
Vol 50 (2) ◽  
pp. 335-341
Author(s):  
P. Deevanhxay ◽  
T. Sasabe ◽  
S. Tsushima ◽  
S. Hirai

1968 ◽  
Vol 46 (22) ◽  
pp. 3579-3586 ◽  
Author(s):  
T. A. Ford ◽  
Michael Falk

The absorption bands due to the OH and OD stretching vibrations of HDO in ice were measured between 0 and −182° and compared with the corresponding bands in liquid water. Their frequencies were correlated with the intermolecular potential energies of H2O and D2O. The distributions of the intermolecular energies in ice and in water at different temperatures were derived from the profiles of the bands.


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