An Examination of Froude-Supercritical Flows and Cyclic Steps On A Subaqueous Lacustrine Delta, Lake Chelan, Washington, U.S.A

2015 ◽  
Vol 85 (7) ◽  
pp. 754-767 ◽  
Author(s):  
Aaron T. Fricke ◽  
Benjamin A. Sheets ◽  
Charles A. Nittrouer ◽  
Mead A. Allison ◽  
Andrea S. Ogston
Keyword(s):  
Lacustrine Delta ◽  
Supercritical Flows

Two-dimensional leaps in near-critical flow over isolated orography

2005 ◽  
Vol 461 (2064) ◽  
pp. 3747-3763 ◽  
Author(s):  
E.R Johnson ◽  
G.G Vilenski
Keyword(s):  
Unsteady Flow ◽  
Equations Of Motion ◽  
Fold Increase ◽  
Flow Speed ◽  
Two Dimensional ◽  
Subcritical Flow ◽  
One Dimensional ◽  
Petviashvili Equation ◽  
Lee Wave ◽  
Supercritical Flows

This paper describes steady two-dimensional disturbances forced on the interface of a two-layer fluid by flow over an isolated obstacle. The oncoming flow speed is close to the linear longwave speed and the layer densities, layer depths and obstacle height are chosen so that the equations of motion reduce to the forced two-dimensional Korteweg–de Vries equation with cubic nonlinearity, i.e. the forced extended Kadomtsev–Petviashvili equation. The distinctive feature noted here is the appearance in the far lee-wave wake behind obstacles in subcritical flow of a ‘table-top’ wave extending almost one-dimensionally for many obstacles widths across the flow. Numerical integrations show that the most important parameter determining whether this wave appears is the departure from criticality, with the wave appearing in slightly subcritical flows but being destroyed by two-dimensional effects behind even quite long ridges in even moderately subcritical flow. The wave appears after the flow has passed through a transition from subcritical to supercritical over the obstacle and its leading and trailing edges resemble dissipationless leaps standing in supercritical flow. Two-dimensional steady supercritical flows are related to one-dimensional unsteady flows with time in the unsteady flow associated with a slow cross-stream variable in the two-dimensional flows. Thus the wide cross-stream extent of the table-top wave appears to derive from the combination of its occurrence in a supercritical region embedded in the subcritical flow and the propagation without change of form of table-top waves in one-dimensional unsteady flow. The table-top wave here is associated with a resonant steepening of the transition above the obstacle and a consequent twelve-fold increase in drag. Remarkably, the table-top wave is generated equally strongly and extends laterally equally as far behind an axisymmetric obstacle as behind a ridge and so leads to subcritical flows differing significantly from linear predictions.

Comparison principles for free-surface flows with gravity

1991 ◽  
Vol 230 ◽  
pp. 231-243 ◽  
Author(s):  
Walter Craig ◽  
Peter Sternberg
Keyword(s):  
Solitary Waves ◽  
Finite Depth ◽  
Free Surface Flows ◽  
Immiscible Fluids ◽  
Steady Flows ◽  
Two Dimensional ◽  
Surface Flows ◽  
Ship Hulls ◽  
Geometrical Information ◽  
Supercritical Flows

This article considers certain two-dimensional, irrotational, steady flows in fluid regions of finite depth and infinite horizontal extent. Geometrical information about these flows and their singularities is obtained, using a variant of a classical comparison principle. The results are applied to three types of problems: (i) supercritical solitary waves carrying planing surfaces or surfboards, (ii) supercritical flows past ship hulls and (iii) supercritical interfacial solitary waves in systems consisting of two immiscible fluids.

Airfoil Design in Subcritical and Supercritical Flows

1979 ◽  
Vol 46 (4) ◽  
pp. 761-766 ◽  
Author(s):  
W. C. Chin ◽  
D. P. Rizzetta
Keyword(s):  
Reasonable Agreement ◽  
Relaxation Method ◽  
Supercritical Pressure ◽  
Small Disturbance ◽  
Trailing Edge ◽  
Difference Analysis ◽  
Pressure Distributions ◽  
Basic Ideas ◽  
New Formulation ◽  
Supercritical Flows

The “inverse” or “design” problem in aerodynamics, which solves for the airfoil shape that induces a prescribed chordwise surface pressure subject to additional requirements on trailing edge closure, is considered in the transonic small-disturbance limit. A new formulation for the stream function ψ is suggested which uses well-set Neumann conditions on the chordwise slit, with the degree of closure dictated by a specified jump in ψ across the downstream slit emanating from the trailing edge. The boundary-value problem is solved by a type-dependent relaxation method that automatically generates closed airfoils on convergence. Computed airfoil shapes using subcritical and supercritical pressure distributions obtained from existing finite-difference analysis codes, in the latter case, with and without shockwaves, give results in reasonable agreement with the original specified shapes, and validate the basic ideas.

New Syphon for Subcritical and Supercritical Flows

1978 ◽  
Vol 104 (4) ◽  
pp. 442-446
Author(s):  
H. Ali Șenturk ◽  
Vedat M. Bașak ◽  
Toraman Șahin
Keyword(s):  
Supercritical Flows

An Unusual Lacustrine Delta

Science ◽  
1949 ◽  
Vol 110 (2846) ◽  
pp. 70-70
Author(s):  
C. N. Savage
Keyword(s):  
Lacustrine Delta

Applicability of Preissmann box scheme for calculation of transcritical flow in pipes

2019 ◽  
Vol 19 (5) ◽  
pp. 1429-1437
Author(s):  
Yanmei Wang ◽  
Chengcai Zhang ◽  
Zhansong Li ◽  
Bin Sun ◽  
Haolan Zhou
Keyword(s):  
Numerical Model ◽  
Momentum Equation ◽  
Internal Boundary ◽  
Urban Drainage ◽  
Box Scheme ◽  
Pipe Networks ◽  
Wide Range ◽  
Transcritical Flow ◽  
Transcritical Flows ◽  
Supercritical Flows

Abstract The accurate computer simulation of pipe flow is of great importance in the design of urban drainage. The Preissmann box scheme is usually used to model a wide range of subcritical and supercritical flows. However, care must be taken over the modelling of transcritical flows since, unless the correct internal boundary conditions are imposed, the scheme becomes unstable. In this paper, using the scheme in conjunction with the reduced momentum equation and applying boundary condition structure inherent to subcritical flow to all regimes, is an approach that enables efficient numerical simulation of transcritical flows in pipe networks. The approach includes three steps. First, a unified mathematical model which is based on the Preissmann slot model is derived. Second, the Preissmann box scheme is used to solve the set of equations, by analyzing and discussing the origin of the invalidity of applying the scheme, and a numerical model suitable for transcritical flow is proposed by the method of changing the convection acceleration term. Third, the numerical model is assessed by comparison with analytical, experimental and numerical results. The proposed models verified that this method can make the Preissmann box scheme applicable to the computation of transcritical flow in pipes.

scholarly journals Un Modelo Numérico 1D en Volúmenes Finitos para la Solución de las Ecuaciones de Flujo e Infiltración del Riego por Gravedad en Melgas

2019 ◽  
pp. 22-30
Keyword(s):  
Numerical Scheme ◽  
Finite Volumes ◽  
Computational Tool ◽  
Important Paper ◽  
Water Load ◽  
El Sistema ◽  
Longitudinal Slope ◽  
Richards’S Equation ◽  
Supercritical Flows ◽  
The Mathematical Model

Un Modelo Numérico 1D en Volúmenes Finitos para la Solución de las Ecuaciones de Flujo e Infiltración del Riego por Gravedad en Melgas A Numerical Model 1D in Finite Volumes for the Solution of the Equations of Flow and Infiltration of the Gravity in Border Irrigation Pino Vargas Edwin, Mejía Marcacuzco J. Abel, Chávarri Velarde Eduardo Universidad Nacional Jorge Basadre Grohmann, Tacna, Perú Universidad Nacional Agraria La Molina, Lima, Perú DOI: https://doi.org/10.33017/RevECIPeru2012.0006/ RESUMEN El desarrollo de este modelo permitirá contar con una herramienta computacional para diseñar adecuadamente el sistema de riego por melgas, reduciendo las pérdidas de agua y utilizándola de manera optima para mejorar la productividad de los cultivos, bajo las premisas de uso eficiente de agua, es decir cultivos de mayor productividad, al más bajo consumo de agua, usando metodologías de producción óptimas. Se implemento el esquema numérico en volúmenes finitos para las ecuaciones de flujo Saint Venant, lo cual permitió conocer el perfil de flujo superficial y la infiltración en el suelo según el avance del riego. Luego del proceso de simulación de varios casos se logro establecer que pendiente longitudinal juega un papel importante en el flujo para las melgas según el modelo planteado se tiene que la pendiente debe ser menor 0,001 m/m. Las pendientes mayores generan flujos rápidos o súper críticos lo cual no es recomendable en el diseño de las melgas, puesto que será una fuente directa de erosión. En cuanto a los caudales de ingreso a las melgas la bibliografía señala un rango para melgas de 1 a 5 l/s/m, lo cual ha sido empleado en el modelo sin ningún inconveniente. En este trabajo se reduce la ecuación de Richards a su expresión unidimensional más su componente temporal y los resultados cumplen satisfactoriamente el objetivo de predecir el movimiento del agua en el subsuelo a partir de datos de propiedades físicas de los suelos y condiciones impuestas tipo dirichlet de carga de agua sobre el suelo. En cuanto a la validación del modelo matemático con datos referenciales de trabajos de investigación se uso el trabajo realizado por Saucedo (2005) para el flujo en superficie y Dahualde G. (2005) para el proceso de infiltración. Se puede contrastar los resultados con algunas diferencias atribuibles a la solución de las ecuaciones, al método numérico empleado y el esquema de solución. Descriptores: Flujo Superficial, Volúmenes Finitos, Infiltración, Modelamiento Numérico 1D, Melgas. ABSTRACT The development of this model will allow to possess a computational tool to design adequately the system of border irrigation, reducing the water loss and using in an ideal way to improve the productivity of the cultures, under the premises of efficient use of water, that is to say cultures of major productivity, to the lowest consumption of water, using methodologies of production optimal. Was implemented the numerical scheme in finite volumes for the equations of flow Saint Venant, which allowed knowing the profile of superficial flow and the infiltration in the soil according to the advance of the irrigation. After the process of simulation of several, cases, was managed to establish that the longitudinal slope plays an important paper in the flow for the border irrigation according to the raised model the slope must be minor 0,001 m/m. The major slopes generate rapid or supercritical flows, which is not advisable in the design of the border irrigation, since it will be a direct source of erosion. As for flows of revenue of border irrigation the bibliography indicates a range from 1 to 5 l/s/m, which has been an employee in the model without any disadvantage. In this work Richards's equation is diminishes to his expression unidimensional more his temporary component and the results fulfill satisfactorily the aim to predict the movement of the water in the subsoil, from information of physical properties of the soils 23 and imposed conditions dirichlet type of water load on the soil. As for the validation of the mathematical model with referential data of works of investigation was used the work realized by Osier-bed (2005) for the flow in surface and Dahualde G. (2005) for the process of infiltration. It is possible to confirm the results with some differences attributable to the solution of the equations, to the numerical used method and the scheme of solution. Keywords: Superficial flow, Finite Volumes, Infiltration, Numerical Modeling 1D, Border Irrigation.

Global controllability between steady supercritical flows in channel networks

2004 ◽  
Vol 27 (7) ◽  
pp. 781-802 ◽  
Author(s):  
Martin Gugat ◽  
Günter Leugering ◽  
E. J. P. Georg Schmidt
Keyword(s):  
Channel Networks ◽  
Global Controllability ◽  
Supercritical Flows
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