scholarly journals Escape probability, mean residence time and geophysical fluid particle dynamics

1999 ◽  
Vol 133 (1-4) ◽  
pp. 23-33 ◽  
Author(s):  
James R Brannan ◽  
Jinqiao Duan ◽  
Vincent J Ervin
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Particle Dynamics ◽  
Fluid Particle ◽  
Escape Probability

scholarly journals Escape probability and mean residence time in random flows with unsteady drift

2001 ◽  
Vol 7 (1) ◽  
pp. 55-65 ◽  
Author(s):  
James R. Brannan ◽  
Jinqiao Duan ◽  
Vincent J. Ervin
Keyword(s):  
Partial Differential Equations ◽  
Residence Time ◽  
Mean Residence Time ◽  
Fluid Transport ◽  
Flow Model ◽  
Tidal Flow ◽  
Numerical Algorithms ◽  
Velocity Fields ◽  
Escape Probability ◽  
Random Flows

We investigate fluid transport in random velocity fields with unsteady drift. First, we propose to quantify fluid transport between flow regimes of different characteristic motion, by escape probability and mean residence time. We then develop numerical algorithms to solve for escape probability and mean residence time, which are described by backward Fokker-Planck type partial differential equations. A few computational issues are also discussed. Finally, we apply these ideas and numerical algorithms to a tidal flow model.

Precipitation and filtration of zinc, magnesium, copper and aluminium hydroxides

1982 ◽  
Vol 47 (12) ◽  
pp. 3362-3370
Author(s):  
Otakar Söhnel ◽  
Eva Matějčková
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Filtration Resistance ◽  
Filtration Pressure ◽  
Bed Porosity ◽  
The Mean ◽  
Filtration Properties

Filtration properties of batchwise precipitated suspensions of Zn(OH)2, Mg(OH)2 and Cu(OH)2 and continuously precipitated Al(OH)3 were studied. For batchwise precipitated suspensions was verified the theoretically predicted dependence of specific filtration resistance on initial supersaturation and for the continuously precipitated Al(OH)3 the relation between the specific filtration resistance and the mean residence time of suspension in the reactor. Dependences were also recorded between the bed porosity and concentration of precipitated solutions, specific filtration resistance and used filtration pressure and the effect of aging of the batchwise precipitated suspension of Mg(OH)2on its filtration properties. The used CST method for determination of filtration characteristics of Zn(OH)2 suspension was also studied.

Nitrogen use efficiency: does a trade-off exist between the N productivity and the mean residence time within species?

2008 ◽  
Vol 56 (3) ◽  
pp. 272 ◽  
Author(s):  
Zhi Y. Yuan ◽  
Han Y. H. Chen ◽  
Ling H. Li
Keyword(s):  
Residence Time ◽  
Nitrogen Use Efficiency ◽  
Mean Residence Time ◽  
Negative Relationship ◽  
Controlled Experiments ◽  
Nitrogen Use ◽  
Trade Off ◽  
N Supply ◽  
Use Efficiency ◽  
The Mean

Nitrogen use efficiency (NUE) can be divided into two components, i.e. N productivity (A) and the mean residence time (MRT). Controlled experiments indicate that there is not a trade-off between A and MRT within species, but this theory has not been well tested in field conditions. Here, we studied the A, MRT and NUE of Stipa krylovii Roshev. in a grassland over 4 years of N fertilisation experimentation. The three parameters (A, MRT and NUE) were significantly related to soil N supply and there was a negative relationship between A and MRT within this species (r = –0.775, P < 0.05), i.e. plants with higher A had lower MRT. Our results showed a trade-off between A and MRT within this Stipa species and this observed trade-off was attributed to different responses of A and MRT to soil fertility.

scholarly journals Struvite recovery from solution containing phosphate(V) and sulphate(VI) ions

2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Nina Hutnik ◽  
Anna Kozik ◽  
Krzysztof Piotrowski ◽  
Andrzej Matynia
Keyword(s):  
Product Quality ◽  
Constant Temperature ◽  
Residence Time ◽  
Mean Residence Time ◽  
Crystallization Process ◽  
Magnesium Ions ◽  
Ammonium Ions ◽  
Internal Circulation ◽  
Mean Size ◽  
Type Crystallizer

AbstractThe research results concerning the application of magnesium and ammonium ions for continuous removal of phosphate(V) ions from solution containing 1.0 or 0.20 mass% of PO43– and from 0.10 to 0.50 mass% of SO42– are presented. A continuous struvite MgNH4PO4 × 6H2O reaction crystallization process was carried out both under stoichiometric conditions and using 20% excess of magnesium ions. The research was conducted in a DT MSMPR type crystallizer with internal circulation of suspension driven by a propeller stirrer, in constant temperature 298 K. The pH varied from 9 to 11 and mean residence time of suspension in a crystallizer τ varied from 900 to 3600 s. It was concluded, that sulphate(VI) ions influenced product quality disadvantageously. Depending on process parameter combinations struvite crystals of mean size from ca. 18 to ca. 44 μm and of moderate homogeneity: CV 7–95% were produced. Presence of sulphate(VI) ions favored crystallization of struvite as prismatic crystals, but tubular forms were also identified. The best shaped struvite crystals were produced at relatively low concentration of sulphate(VI) ions, pH 9 and for mean residence time of suspension in a crystallizer elongated up to 3600 s.

Mean Residence Time of a Liquid in a Trickling Filter

1959 ◽  
Vol 85 (6) ◽  
pp. 51-78 ◽  
Author(s):  
Morton D. Sinkoff ◽  
Ralph Porges ◽  
James H. McDermott
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Trickling Filter

Two Algorithms for Solving Coupled Particle Dynamics and Flow Field Equations in Two-Phase Flows

2010 ◽  
Author(s):  
R. Kamali ◽  
S. A. Shekoohi
Keyword(s):  
Flow Field ◽  
Particle Dynamics ◽  
Fluid Particle ◽  
Navier Stokes ◽  
Test Cases ◽  
Particle Interactions ◽  
Field Equations ◽  
Two Phase ◽  
Coupled Equations ◽  
Solution Accuracy

Two methods for solving coupled particle dynamics and flow field equations simultaneously by considering fluid-particle interactions to simulate two-phase flow are presented and compared. In many conditions, such as magnetic micro mixers and shooting high velocity particles in fluid, the fluid-particle interactions can not be neglected. In these cases it is necessary to consider fluid-particle interactions and solve the related coupled equations simultaneously. To solve these equations, suitable algorithms should be used to improve convergence speed and solution accuracy. In this paper two algorithms for solving coupled incompressible Navier-Stokes and particle dynamics equations are proposed and their efficiencies are compared by using them in a computer program. The main criterion that is used for comparison is the time they need to converge for a specific accuracy. In the first algorithm the particle dynamics and flow field equations are solved simultaneously but separately. In the second algorithm in each iteration for solving flow field equations, the particle dynamics equation is also solved. Results for some test cases are presented and compared. According to the results the second algorithm is faster than the first one especially when there is a strong coupling between phases.

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