Seepage flow through simulated grounded ice jam

1985 ◽  
Vol 12 (4) ◽  
pp. 926-929 ◽  
Author(s):  
J. Wong ◽  
S. Beltaos ◽  
B. G. Krishnappan
Keyword(s):  
Unsteady Flow ◽  
Laboratory Tests ◽  
Seepage Flow ◽  
Flow Conditions ◽  
Local Flow ◽  
Ice Jam ◽  
Flow Through ◽  
Water Depths

Laboratory tests were conducted to study the seepage flow conditions through a simulated grounded jam. Results indicated that nonlaminar seepage predominates and that the resulting relationship between the local flow and the upstream and downstream water depths may be applied to both steady and unsteady flow conditions.

Laboratory tests on surges created by ice jam releases

1985 ◽  
Vol 12 (4) ◽  
pp. 930-933 ◽  
Author(s):  
J. Wong ◽  
S. Beltaos ◽  
B. G. Krishnappan
Keyword(s):  
Unsteady Flow ◽  
Laboratory Tests ◽  
Water Levels ◽  
Flow Conditions ◽  
Ice Jam ◽  
Discernible Effect

Laboratory tests were conducted to investigate the unsteady-flow conditions after the release of an ice jam. The tests revealed that the presence of the moving ice has no discernible effect on the characteristics of the surge that follows the release of the jam and that the model of S. Beltaos and B. G. Krishnappan gives good predictions of the water levels and fair predictions of the water speeds.

Flow through the voids of breakup ice jams

1999 ◽  
Vol 26 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Spyros Beltaos
Keyword(s):  
Numerical Modelling ◽  
River Discharge ◽  
Integral Method ◽  
Laboratory Tests ◽  
Major Portion ◽  
Ice Jams ◽  
Ice Jam ◽  
Flow Through

Flow through the voids of breakup ice jams can be a major portion of the total river discharge, especially where the jam is so thick as to be grounded. Very little information is available on this question; it is derived from laboratory tests or from numerical modelling applications, and there is a discrepancy between respective seepage coefficients. A field program has been carried out to measure the flow through the voids in ice jams by taking advantage of favourable access conditions created by an ice-retention structure on the Credit River. The data obtained during two breakup events are described and an integral method of analysis is developed to identify areas of grounding and determine seepage coefficients. Values of the latter are in agreement with those deduced by numerical modelling.Key words: flow, ice jam, modelling, seepage, voids.

Numerical computation of river ice jams

1993 ◽  
Vol 20 (1) ◽  
pp. 88-99 ◽  
Author(s):  
S. Beltaos
Keyword(s):  
Numerical Model ◽  
Field Data ◽  
Seepage Flow ◽  
Water Levels ◽  
Full Potential ◽  
Ice Jams ◽  
Ice Jam ◽  
Natural Stream ◽  
Flow Through ◽  
Made In

A numerical model called RIVJAM has been developed to compute the configuration of and water levels caused by ice jams of the "wide" kind, under natural stream conditions and regardless of whether the jam has attained its full potential, known as equilibrium. Account of seepage flow through the voids of the jam enables predictions of grounding conditions to be made, in accord with observations. The model is applied to three case studies of ice jam events and found to perform satisfactorily. The various model coefficients fall within the expected ranges, with the exception of a parameter characterizing the intensity of seepage flow. More field data are needed to elucidate this matter. Key words: grounding, ice, jam, model, numerical, river, seepage, thickness, toe, wide.

Unsteady Flow through a Four-Way Branch in the Exhaust System of a Multi-Cylinder Engine

1971 ◽  
Vol 13 (4) ◽  
pp. 253-265 ◽  
Author(s):  
H. Daneshyar ◽  
R. D. Pearson
Keyword(s):  
Unsteady Flow ◽  
Steady Flow ◽  
Exhaust System ◽  
Flow Conditions ◽  
Pressure Coefficients ◽  
Lower Accuracy ◽  
Method Of Solution ◽  
Convergent Method ◽  
Flow Through ◽  
Flow Variables

This paper is concerned with the investigation of unsteady flow through a four-way branch, with particular reference to its application to flow in the exhaust system of a multi-cylinder engine. The only methods of solution hitherto available are for unsteady flow through a three-way branch. The potentially most accurate theory of those reported takes pressure and entropy changes at the junction into account, but cannot be used in practice since the iterative processes employed in this method often become divergent (I)‡. A convergent method of solution has therefore been developed and is utilized to study the unsteady flow through a four-way branch, making the usual assumption of quasi-steady flow at the junction. A general computer programme for multi-cylinder engines combining the programmes for the cylinder boundary, for the nozzle boundary, for unsteady flow in the pipes, and the present method for branched systems has been developed (in Algol code) to compute the flow variables (pressure, velocity, and temperature) in the exhaust system and cylinders. The temperature variations which can arise in an engine are fully taken into account. Experimental data are presented for both steady and unsteady flow conditions. The steady data have been used to supply the pressure coefficients needed for full computation in the non-steady flow case. Simpler theories involving assumed pressure coefficients are also employed in shorter programmes which yield acceptable results of lower accuracy. Consequently, it appears that prediction can now be made to sufficient accuracy, in the range of pressure amplitudes and Mach numbers investigated, without the need for comprehensive steady flow testing.

scholarly journals DRAG COEFFICIENT OF VEGETATION IN FLOW MODELING

2012 ◽  
Vol 1 (33) ◽  
pp. 4
Author(s):  
Zhan Hu ◽  
M. Stive ◽  
T. Zitman ◽  
T. Suzuki
Keyword(s):  
Drag Coefficient ◽  
Numerical Models ◽  
Flow Conditions ◽  
Mean Velocity ◽  
Local Flow ◽  
Rigid Vegetation ◽  
Flow Through ◽  
The Mean ◽  
Empirical Coefficients

Flow through vegetation has a significant impact on sediment transport and ecosystem robustness in the coastal and fluvial environment. Numerical models (Nepf and Vivoni, 2000; Uittenbogaaard, 2003) have been developed to simulate this type of flow. The success of these models depends on proper characterization of the main processes and appropriate setting of pre-defined empirical coefficients. Among others, the drag coefficient CD is one of the most important coefficients, which influences the mean velocity and the turbulence characteristics (Nepf and Ghisalberti, 2008). Tanino and Nepf (2008) and Cheng (2011) have derived empirical relationships of CD for flow through emerged rigid vegetation. Both studies confirm that CD is related to canopy properties (plants density, diameter, etc.) as well as flow conditions. However, in both studies CD is estimated by simply equating the vegetation drag force to the water level gradient. Bed shear stress and Reynolds stress were ignored. More importantly, the CD provided by these expressions is depth averaged, which is not suitable for modelling flow and canopy that both vary in vertical (Nepf and Vivoni, 2000). In this study, the CD relation proposed by Cheng (2011) is modified. This new relation depends on the local flow conditions and canopy properties in the vertical. Further, this relation is implemented in an iterative scheme of a 1DV flow model. The modelling results are compared with experiment data of flow through emerged and submerged rigid vegetation. Our results show that when special defined Reynolds number is small, this relation performs less well compare to that when it is larger.

The Matching of Diesel Engine to Exhaust Turbocharger—Improved Calculation Model at T-Junction

1988 ◽  
Vol 110 (3) ◽  
pp. 547-551 ◽  
Author(s):  
T. Morimune ◽  
N. Hirayama
Keyword(s):  
Diesel Engine ◽  
Unsteady Flow ◽  
Gas Flow ◽  
Constant Pressure ◽  
Computer Time ◽  
Calculation Model ◽  
Flow Conditions ◽  
Flow Through ◽  
Time Required ◽  
Unsteady Gas Flow

The suitability of the analysis of the unsteady flow through the exhaust junction plays an important role in developing a computer program for matching a diesel engine to an exhaust turbocharger. This paper describes an improvement of the calculation procedure for computing the behavior of the unsteady gas flow at the exhaust junction. Measured values of pressure, temperature, and mass flow rate are compared with computer predictions using four different pipe junction computations: constant pressure model, momentum model, simplified model, and the improved exact model developed in this study. This comparison shows that the new technique gives the best agreement with the measured values, while the computer time required is twice as long. Under unsteady flow conditions the exhaust junction gives six types of flow configuration, and calculations indicate that only some of these types of flow dominate; the rest occur for only short intervals.

The Estimation of Discharge in an Experimental Open Channel

2014 ◽  
Vol 905 ◽  
pp. 369-373
Author(s):  
Choo Tai Ho ◽  
Yoon Hyeon Cheol ◽  
Yun Gwan Seon ◽  
Noh Hyun Suk ◽  
Bae Chang Yeon
Keyword(s):  
Unsteady Flow ◽  
River Discharge ◽  
Open Channel ◽  
Flow Conditions ◽  
Mean Velocity ◽  
Velocity Equation ◽  
The Mean ◽  
Loop Form

The estimation of a river discharge by using a mean velocity equation is very convenient and rational. Nevertheless, a research on an equation calculating a mean velocity in a river was not entirely satisfactory after the development of Chezy and Mannings formulas which are uniform equations. In this paper, accordingly, the mean velocity in unsteady flow conditions which are shown loop form properties was estimated by using a new mean velocity formula derived from Chius 2-D velocity formula. The results showed that the proposed method was more accurate in estimating discharge, when compared with the conventional formulas.

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