Evaluation of a first-order water transfer term for variably saturated dual-porosity flow models

1993 ◽  
Vol 29 (4) ◽  
pp. 1225-1238 ◽  
Author(s):  
H. H. Gerke ◽  
M. T. van Genuchten
Keyword(s):  
Water Transfer ◽  
Dual Porosity ◽  
Flow Models ◽  
First Order ◽  
Transfer Term

Dual EKF State and Parameter Estimation in Multi-Class First-Order Traffic Flow Models

2008 ◽  
Vol 41 (2) ◽  
pp. 14078-14083 ◽  
Author(s):  
J.W.C. Van Lint ◽  
Serge P. Hoogendoorn ◽  
A. Hegyi
Keyword(s):  
Parameter Estimation ◽  
Traffic Flow ◽  
Flow Models ◽  
First Order ◽  
Traffic Flow Models

First-order traffic flow models incorporating capacity drop: Overview and real-data validation

2017 ◽  
Vol 106 ◽  
pp. 52-75 ◽  
Author(s):  
Maria Kontorinaki ◽  
Anastasia Spiliopoulou ◽  
Claudio Roncoli ◽  
Markos Papageorgiou
Keyword(s):  
Traffic Flow ◽  
Real Data ◽  
Data Validation ◽  
Flow Models ◽  
First Order ◽  
Traffic Flow Models ◽  
Capacity Drop

A comparative study of two-phase flow models relevant to bubble column dynamics

1999 ◽  
Vol 394 ◽  
pp. 73-96 ◽  
Author(s):  
P. D. MINEV ◽  
U. LANGE ◽  
K. NANDAKUMAR
Keyword(s):  
Bubble Column ◽  
Bubbly Flows ◽  
Necessary Condition ◽  
Qualitative Behaviour ◽  
Two Phase ◽  
Weakly Nonlinear ◽  
Flow Models ◽  
First Order ◽  
Column Dynamics ◽  
Permanent Wave

Multiphase flow modelling is still a major challenge in fluid dynamics and, although many different models have been derived, there is no clear evidence of their relevance to certain flow situations. That is particularly valid for bubbly flows, because most of the studies have considered the case of fluidized beds. In the present study we give a general formulation to five existing models and study their relevance to bubbly flows. The results of the linear analysis of those models clearly show that only two of them are applicable to that case. They both show a very similar qualitative linear stability behaviour. In the subsequent asymptotic analysis we derive an equation hierarchy which describes the weakly nonlinear stability of the models. Their qualitative behaviour up to first order with respect to the small parameter is again identical. A permanent-wave solution of the first two equations of the hierarchy is found. It is shown, however, that the permanent-wave (soliton) solution is very unlikely to occur for the most common case of gas bubbles in water. The reason is that the weakly nonlinear equations are unstable due to the low magnitude of the bulk modulus of elasticity. Physically relevant stabilization can eventually be achieved using some available experimental data. Finally, a necessary condition for existence of a fully nonlinear soliton is derived.

scholarly journals Numerical evaluation of a second-order water transfer term for variably saturated dual-permeability models

2004 ◽  
Vol 40 (7) ◽  
Author(s):  
J. Maximilian Köhne ◽  
Binayak P. Mohanty ◽  
Jirka Simunek ◽  
Horst H. Gerke
Keyword(s):  
Numerical Evaluation ◽  
Water Transfer ◽  
Second Order ◽  
Transfer Term

Introducing Buses into First-Order Macroscopic Traffic Flow Models

1998 ◽  
Vol 1644 (1) ◽  
pp. 70-79 ◽  
Author(s):  
J.P. Lebacque ◽  
J.B. Lesort ◽  
F. Giorgi
Keyword(s):  
Simple Model ◽  
Traffic Flow ◽  
Supply And Demand ◽  
Interaction Model ◽  
Macroscopic Model ◽  
Moving Frame ◽  
Large Measure ◽  
Flow Models ◽  
First Order ◽  
Traffic Flow Models

The aim of this paper is to provide a simple model of the interaction between buses and the surrounding traffic flow. Traffic flow is assumed to be described by a first-order macroscopic model of the Lighthill-Whitman-Richards type. As a consequence of their kinematics, which in large measure can be considered to be independent of the flow of other vehicles, buses should be considered as a moving capacity restriction from the point of view of other drivers. This simple interaction model is analyzed, mainly by considering the moving frame associated with the bus in order to derive analytical computation rules for derivation of the effects of the presence of the bus in the traffic flow. After deriving traffic equations in the moving frame associated with a bus, the usual basic concepts of first-order models, including those of relative traffic supply and demand, are generalized to the moving frame. A simple model for the bus-traffic interaction, assuming that the dimension of the bus can be neglected, can be derived from analytical calculations in the moving frame. Finally, some tentative results for the inclusion of buses into first-order traffic flow models, discretized according to Godunov’s scheme, are given.

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