scholarly journals Transient forcing effects on mixing of two fluids for a stable stratification

2016 ◽  
Vol 52 (9) ◽  
pp. 7178-7197 ◽  
Author(s):  
María Pool ◽  
Marco Dentz ◽  
Vincent E. A. Post
Keyword(s):  
Stable Stratification ◽  
Two Fluids ◽  
Transient Forcing

Mathematical modeling of steady stratified flows

2003 ◽  
Vol 3 ◽  
pp. 195-207
Author(s):  
A.M. Ilyasov ◽  
V.N. Kireev ◽  
S.F. Urmancheev ◽  
I.Sh. Akhatov
Keyword(s):  
Stokes Equations ◽  
Approximate Model ◽  
Immiscible Liquid ◽  
Stratified Flows ◽  
Navier Stokes ◽  
Flat Channel ◽  
Navier Stokes Equations ◽  
Two Fluids ◽  
Flow Parameters ◽  
Direct Numerical Solution

The work is devoted to the analysis of the flow of immiscible liquid in a flat channel and the creation of calculation schemes for determining the flow parameters. A critical analysis of the well-known Two Fluids Model was carried out and a new scheme for the determination of wall and interfacial friction, called the hydraulic approximation in the theory of stratified flows, was proposed. Verification of the proposed approximate model was carried out on the basis of a direct numerical solution of the Navier–Stokes equations for each fluid by a finite-difference method with phase-boundary tracking by the VOF (Volume of Fluid) method. The graphical dependencies illustrating the change in the interfase boundaries of liquids and the averaged over the occupied area of the phase velocities along the flat channel are presented. The results of comparative calculations for two-fluid models are also given, according to the developed model in the hydraulic approximation and direct modeling. It is shown that the calculations in accordance with the hydraulic approximation are more consistent with the simulation results. Thus, the model of hydraulic approximation is the most preferred method for calculating stratified flows, especially in cases of variable volumetric content of liquids.

scholarly journals A Climatology of Nocturnal Low-Level Jets at Cabauw

2009 ◽  
Vol 48 (8) ◽  
pp. 1627-1642 ◽  
Author(s):  
P. Baas ◽  
F. C. Bosveld ◽  
H. Klein Baltink ◽  
A. A. M. Holtslag
Keyword(s):  
Wind Speed ◽  
Ground Level ◽  
Geostrophic Wind ◽  
Stable Stratification ◽  
Radiative Cooling ◽  
Inertial Oscillation ◽  
Stable Boundary Layers ◽  
Above Ground Level ◽  
Low Level ◽  
Low Level Jets

Abstract A climatology of nocturnal low-level jets (LLJs) is presented for the topographically flat measurement site at Cabauw, the Netherlands. LLJ characteristics are derived from a 7-yr half-hourly database of wind speed profiles, obtained from the 200-m mast and a wind profiler. Many LLJs at Cabauw originate from an inertial oscillation, which develops after sunset in a layer decoupled from the surface by stable stratification. The data are classified to different types of stable boundary layers by using the geostrophic wind speed and the isothermal net radiative cooling as classification parameters. For each of these classes, LLJ characteristics like frequency of occurrence, height above ground level, and the turning of the wind vector across the boundary layer are determined. It is found that LLJs occur in about 20% of the nights, are typically situated at 140–260 m above ground level, and have a speed of 6–10 m s−1. Development of a substantial LLJ is most likely to occur for moderate geostrophic forcing and a high radiative cooling. A comparison with the 40-yr ECMWF Re-Analysis (ERA-40) is added to illustrate how the results can be used to evaluate the performance of atmospheric models.

scholarly journals STUDIES ON THE CHEMISTRY OF SEROUS EFFUSIONS

1914 ◽  
Vol 20 (4) ◽  
pp. 334-345 ◽  
Author(s):  
Albert A. Epstein
Keyword(s):  
Blood Serum ◽  
Protein Content ◽  
Chloride Content ◽  
Normal Blood ◽  
Pleural Effusions ◽  
Albumin Ratio ◽  
Two Fluids ◽  
Low Protein ◽  
Comparison Of The Results ◽  
Purulent Fluid

A comparison of the results obtained in the analysis of the different effusions shows that they vary, (1) according to location, and (2) according to the disease in which they are produced. Thus the subcutaneous effusions are totally different in their composition from the abdominal or pleuritic fluids; and again the abdominal fluid of nephritic origin is different from those of cardiac or other origin. The cutaneous effusions are characterized by a very low protein content and a small amount of incoagulable nitrogen. Of the protein present in these fluids, the globulin constitutes the greater portion. In the mixed cardionephritic fluids the ratio of globulin to albumin is lower than that in normal blood serum; but when compared with the blood sera of cardionephritic cases there appears to be a certain parallelism. The chloride content of these fluids is considerably above that found in normal blood serum, but is comparable with those of corresponding cases. The effusions occurring in serous cavities differ from the cutaneous ones by their higher protein content. The highest values are attained in the pleural fluids, in which the protein present is almost the same as that in normal blood serum. The incoagulable nitrogen in these fluids is uniformly low. The chlorides vary in amount according to the nature of the case. In the effusions of inflammatory origin the values are lower than those found in the blood. In the pleural fluids of other than inflammatory origin the chloride content is either the same or higher than that of blood serum. The globulin-albumin ratio in all of these fluids except one (table III, fluid 61) is higher than that of normal blood serum. Otherwise the highest value is presented by a pleural fluid from a case of nephritis (table III, fluid 205) and the lowest by an empyema fluid (table III, fluid 30). The latter case is of especial interest because of the theory, first propounded by Schmidt, that the leucocytes in the purulent fluid are largely responsible for high globulin content. The abdominal fluids in general are less rich in protein than the pleural effusions. Those of cardiac origin give the highest protein values, but the globulin-albumin ratios are lower than in the pleural fluids or in the blood sera of corresponding cases. Only in two fluids does the globulin reach a percentage of 62 and 52.2. In both these cases the chloride content is also high. The incoagulable nitrogen in all of them is rather low. In one fluid of purely nephritic origin the protein content is low and all of it is globulin. This is suggestive, when compared with the values obtained in the analysis of the blood sera from nephritic cases. The results obtained in the analysis of abdominal fluids from cardionephritic cases approach very closely those obtained in purely cardiac cases.

scholarly journals Physical Acceptability of the Renyi, Tsallis and Sharma-Mittal Holographic Dark Energy Models in the f(T,B) Gravity under Hubble’s Cutoff

Universe ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 67
Author(s):  
Salim Harun Shekh ◽  
Pedro H. R. S. Moraes ◽  
Pradyumn Kumar Sahoo
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
Cosmological Parameters ◽  
Field Equations ◽  
Eos Parameter ◽  
Two Fluids ◽  
Gravitational Field Equations ◽  
Energy Models ◽  
Different Types ◽  
The Universe

In the present article, we investigate the physical acceptability of the spatially homogeneous and isotropic Friedmann–Lemâitre–Robertson–Walker line element filled with two fluids, with the first being pressureless matter and the second being different types of holographic dark energy. This geometric and material content is considered within the gravitational field equations of the f(T,B) (where T is the torsion scalar and the B is the boundary term) gravity in Hubble’s cut-off. The cosmological parameters, such as the Equation of State (EoS) parameter, during the cosmic evolution, are calculated. The models are stable throughout the universe expansion. The region in which the model is presented is dependent on the real parameter δ of holographic dark energies. For all δ≥4.5, the models vary from ΛCDM era to the quintessence era.

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