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Papers by John McCorquodale

Internal Flow in Hydraulic Jumps

Journal of Hydraulic Engineering, May 1, 1983

The hydraulic jump has been extensively studied using physical models; however, very little data ... more The hydraulic jump has been extensively studied using physical models; however, very little data are available for the internal flow in prototype hydraulic jump stilling basins. A mathematical model has been developed to help in the prediction of prototype performance from physical models. The technique used here is an extension of the strip integral method of R. Narayanan. The strip integral method uses velocity shape functions to permit the partial integration of the equations of motion. A Gaussian velocity distribution is used in the mixing zone and the power law is used in the inner layer. The mathematical model includes the bed shear, turbulent shear, the potential core, entrained air, centrifugal force and turbulence pressure. The model gives a fairly good prediction of the jump length, roller length, velocity distribution, water surface and pressure at the bed. The prediction of the growth of the boundary layer was not very good. The model indicated that the main effect of entrained air is the bulking of flow. The effects of centrifugal forces and turbulence pressures increase as F\d1² and start to become significant for F\d1 > 5.

Short Circuiting and Density Interface in Primary Clarifiers

Journal of Hydraulic Engineering, Sep 1, 1994

The unsteady flow regime and the temperature mixing in temperature-stratified settling tanks asso... more The unsteady flow regime and the temperature mixing in temperature-stratified settling tanks associated with a warm influent are investigated by application of a numerical model with two different turbulence models. The model consists of a series of conservation equations for fluid mass, momentum, and temperature, with one version using the algebraic stress model and the other version using the conventional k-ϵ model. The simulation results are compared with existing experimental data for the temperature distribution. The velocity measurements were made under the same laboratory conditions that were used for the temperature surveys. The experimental results are presented and compared with those predicted by the numerical model.

Design of a Hydraulic Control Structure with an in-Spillway Fishpass

Springer eBooks, 1984

The town of Wallaceburg, Ontario, Canada, located on the Sydenham River near its delta at Lake St... more The town of Wallaceburg, Ontario, Canada, located on the Sydenham River near its delta at Lake St. Clair, has a long history of serious flooding due primarily to spring runoff and ice jams. In order to alleviate this flooding, the St. Clair Region Conservation Authority has just completed the construction of a flood control dam and floodway. The scheme which is illustrated in Fig. 1 consists of: (a) a nine kilometre floodway with a grass-lined trapezoidal shape, 3H:1V side slopes and a 70 m bottom width; (b) a trapezoidal drop-structure with a trapezoidal stilling basin to regulate velocities in the floodway and control erosion; (c) a 12 m high earthfilled dam; and (d) a concrete control structure with low level sluiceways.

Grid Turbulence in Hydraulic Models

Journal of Hydraulic Research, Jul 1, 1976

ABSTRACT It is shown that free stream turbulence can cause apparent scale effects in certain hydr... more ABSTRACT It is shown that free stream turbulence can cause apparent scale effects in certain hydraulic models, namely, those involving highly curvilinear flow. These apparent scale effects can be more than triple the normal boundary layer displacement effect.Sluice gate models with variable inclinations were used to investigate this effect. It was found that high free stream turbulence could increase the contraction coefficient by more than 10% relative to the theoretical solution.

Water Science and Technology, Apr 20, 2016

The performance characteristics of relatively shallow (3.3 and 3.7 m sidewater depth in 30.5 m di... more The performance characteristics of relatively shallow (3.3 and 3.7 m sidewater depth in 30.5 m diameter) activated sludge secondary clarifiers were extensively evaluated during a 2-year testing program at the City of Akron Water Reclamation Facility (WRF), Ohio, USA. Testing included hydraulic and solids loading stress tests, and measurement of sludge characteristics (zone settling velocity (ZSV), dispersed and flocculated total suspended solids), and the results were used to calibrate computational fluid dynamic (CFD) models of the various clarifiers tested. The results demonstrated that good performance could be sustained at surface overflow rates in excess of 3 m/h, as long as the clarifier influent mixed liquor suspended solids (MLSS) concentration was controlled to below critical values. The limiting solids loading rate (SLR) was significantly lower than the value predicted by conventional solids flux analysis based on the measured ZSV/MLSS relationship. CFD analysis suggested that this resulted because mixed liquor entering the clarifier was being directed into the settled sludge blanket, diluting it and also creating a 'thin' concentration sludge blanket that overlays the thicker concentration sludge blanket typically expected. These results indicate the need to determine the allowable SLR for shallow clarifiers using approaches other than traditional solids flux analysis. A combination of actual testing and CFD analyses are demonstrated here to be effective in doing so.

Near-field mixing at an outfall

Canadian Journal of Civil Engineering, Feb 1, 1996

The near-field mixing of effluent from buoyant and nonbuoyant flows from outfalls discharging int... more The near-field mixing of effluent from buoyant and nonbuoyant flows from outfalls discharging into a cross-flowing ambient current in trapezoidal channels has been investigated. A physical model was scaled to represent a typical large outfall into one of the connecting channels of the Great Lakes system. The discharged jet was measured in detail to determine the velocity and concentration fields. The excess velocities and concentrations were found to follow the Gaussian distribution. Empirical expressions for the jet trajectories, minimum dilutions, and plume widths were derived. A correction factor has been introduced to the concentration distribution to ensure mass conservation. The calibrated model was verified by comparison with field data and the results of other near-field models (PDS, MIT, and CORMIX). Key words: mixing, near field, pollutant transport, outfall, buoyant flow, non-buoyant flows.

Analysis of the submerged radial hydraulic jump

Canadian Journal of Civil Engineering, Sep 1, 1985

Most of the research work on hydraulic jumps has dealt with their macroscopic behaviour. The impo... more Most of the research work on hydraulic jumps has dealt with their macroscopic behaviour. The important parameters in these studies were the sequent depth ratio and the jump length required for stilling basin design. Unfortunately, the internal flow in submerged radial hydraulic jumps has received very little attention. A complete mathematical model of the internal flow would permit the modeller to assess the possible scale effects in a physical model and to better estimate the cavitation potential.This study treats the internal flow characteristics of the submerged radial hydraulic jumps under different submergence and operating conditions. A numerical model based on the strip integral method is used to solve the governing momentum and continuity equations. The numerical technique uses velocity shape functions to permit the partial integration of the equations of motion. A Gaussian velocity distribution is used in the mixing zone and the power law is used in the inner layer. The model predicts the velocity distribution, water surface profile, decay of the maximum velocity, variation of the surface velocity, sequent depth ratio, jump length, and energy loss.A comprehensive experimental program was conducted in an expanding Plexiglas flume with a total angle of divergence of 13.5°. The results were used to calibrate and validate the model. The model predictions also compared well with the results of other studies.

Supercritical Flow over Sills

Journal of the Hydraulics Division, Apr 1, 1972

A conformal mapping solution for irrotational gravity-free flow is modified to determine an expre... more A conformal mapping solution for irrotational gravity-free flow is modified to determine an expression for the drag on continuous and dentated sills. The effect of gravity is partially accounted for by the inclusion of the upstream hydrostatic force in the momentum equations. For the dentated sill case, continuity, energy and momentum relationships were used to divide the total flow into two portions, i.e., one passing between the baffles and another passing over the baffles. Two-dimensional techniques were then applied to determine the baffle drag coefficient. Good agreement was found between experimental and theoretical drag coefficients for both the continuous and dentated sills for (jet height)/(baffle height) 1.4.

Behaviour of compacted fine-grained soil in a brine environment

Canadian Journal of Civil Engineering, Jun 1, 1984

The hydraulic conductivity and engineering properties of compacted fine-grained soils change with... more The hydraulic conductivity and engineering properties of compacted fine-grained soils change with time when exposed to a 30% NaCl brine environment. The hydraulic conductivity of brine was found to be greater than that of water in soils where the dominant clay mineral was montmorillonite, whereas a soil rich in illite and kaolinite was virtually insensitive to variations in solution composition. Increases in brine hydraulic conductivities were most pronounced in soils high in montmorillonite where sodium was the dominant adsorbed ion. They demonstrated the most labile hydraulic conductivities. Fine-grained soils, high in montmorillonite clay content, were prone to alteration in engineering properties when soaked in a 30% NaCl brine. However, brine soaking had little effect on soils rich in illite–kaolinite.

Ain Shams Engineering Journal, Dec 1, 2018

The spur dikes are structures that usually used for flow diversion from erodible wall and they us... more The spur dikes are structures that usually used for flow diversion from erodible wall and they usually create a appropriate path for directing the flow, flood control, protection of external walls, and some other cases. Through modifying the hydraulic conditions and creation of smooth flow, spur dikes can decrease water erosion force and power of sediment transport. In this study, the channel and spur dike related to the Heltz Laboratory model have been simulated using Flow-3D numerical model. The RNG turbulence model has been applied for turbulence modeling. The turbulent flow field around inclined spur dike and the effect of such parameters as angle, hydraulic conditions and sedimentation pattern have been investigated. The results showed that increasing the angle of spur dike affects the length and width of sedimentation area. When angle of spur dike increases from 90 to 120 deg, the width and length of the sedimentation area will increase up to about 71 and 92 percent, respectively.

Submerged Radial Hydraulic Jump

Journal of the Hydraulics Division, Mar 1, 1980

A slight flaring of the side walls of the stilling basin can be advantageous in reducing the exit... more A slight flaring of the side walls of the stilling basin can be advantageous in reducing the exit velocities. The hydraulic jump in such a stilling basin is referred to as a radial hydraulic jump. When the sluice gates discharge directly to the stilling basin, a submerged radial hydraulic jump will probably occur. An experimental study produced surface profiles, bed pressure and length characteristics for the submerged radial jump. A fourth-degree polynomial was used to describe the surface profile. The submerged radial jump lengths were found to be from 50% to 70% of the corresponding submerged rectangular jump lengths. Improved energy dissipation is also characteristic of the radial jumps. The model consisted of a 1.0-m long stilling basin with a total divergence angle of 13.5? located downstream a sluice gate. A theoretical equation is proposed to describe the relationship among: gate submergence, exit depth, initial depth, initial Froude number and basin divergence.

Radial Hydraulic Jump

Journal of the Hydraulics Division, Sep 1, 1979

Radial hydraulic jump occurs in a stilling basin with diverging side walls. Experimental data is ... more Radial hydraulic jump occurs in a stilling basin with diverging side walls. Experimental data is used to obtain the free-surface profiles and the floor-pressure profiles within the diverging basin. These profiles are used to develop generalized equations for the effective side wall forces for Froude numbers from 2 to 10. The momentum equation, which involves these forces, is then applied to develop an equation for the sequent depth ratio for the jump. For Froude numbers above 3, the sequent depth ratio is shown to be less than that for the rectangular jump. The length of the radial jump is about 70% of the length of a rectangular jump for the same initial Froude number. However, the volume of the jump is approximately the same as for the rectangular jump. The energy dissipation in the radial jump is approx 15% greater than for the rectangular jump.

Influence of skirt radius on performance of circular clarifier with density stratification

International Journal for Numerical Methods in Fluids, Apr 30, 1992

A numerical model for predicting the velocity field and suspended solids distribution in a second... more A numerical model for predicting the velocity field and suspended solids distribution in a secondary circular clarifier with density difference is evaluated. The density effects are characterized by the inlet densimetric Froude number. This study focuses on the role of the reaction baffle position in the performance of the clarifiers. For a large‐radius baffle and low densimetric Froude number an important phenomenon known as the density waterfall occurs in the inlet zone of the clarifiers. This was predicted by the numerical model and confirmed by the physical model tests. This model consists of a series of conservation equations for fluid mass and momentum and sediment concentration. The turbulent stresses are calculated by use of the eddy viscosity concept and the κ–ϵ. turbulence model. The study showed that the density waterfall results in high entrainment and high recirculation. A comparison of the solids concentration distribution for a tank with a small skirt radius to that with a large skirt radius shows that small skirt radius reduces the density waterfall effect and significantly improves the clarifier performance at low densimetric Froude numbers.

Simulation of Curved Open Channel Flows by 3D Hydrodynamic Model

Journal of Hydraulic Engineering, Jul 1, 1998

... Two test cases from curved flumes have been studied: (1) A 270° channel bend with a sloped ou... more ... Two test cases from curved flumes have been studied: (1) A 270° channel bend with a sloped outer bank; and (2) a meandering channel with mass transport. The results are compared with the available data, which shows generally good agreement. ...

Developing State-of-the-Art Hydraulic Model Integrating Hydraulic Profile with Flow Distribution

Proceedings of the Water Environment Federation, 2008

ABSTRACT In a recent project at the Sacramento Regional wastewater treatment plant, a new mathema... more ABSTRACT In a recent project at the Sacramento Regional wastewater treatment plant, a new mathematical hydraulic profile model was developed. The model incorporates advanced flow distribution with basic hydraulic profile modeling. Advanced flow distribution models using two-dimensional computational fluid dynamics and one dimensional energy-momentum models were used to estimate the flow distribution between the different unit processes. The model was then used to determine the hydraulic profile throughout the plant based on the flow distribution. The model was also used to predict flows received by each unit processes. The model was calibrated and verified using field data and physical modeling. The field data was first used to calibrate a 1:20 scale physical model. Detailed description of the model and its application at the Sacramento Regional wastewater treatment plant will be presented in the final manuscript.Few years ago, plant staff initiated a project to develop a hydraulic mathematical model of the treatment plant. The objectives of the mathematical model are: Understand the flow distribution between the different unit processes Identify potential fixes Use the model as operational tool to improve plant performance Different commercially available softwares were evaluated. The criteria used in the evaluation included four categories: 1) Hydraulic modeling category, 2) Code development category, 3) Information system category, 4) Licensing requirement categoryA detailed description of each model selection criteria will be included in the final manuscript.

Power Law for Turbulent Cylindrical Boundary Layers

Journal of the Royal Aeronautical Society, 1971

Considerable research effort has been devoted to the experimental and theoretical study of turbul... more Considerable research effort has been devoted to the experimental and theoretical study of turbulent boundary layers on flat plates. However, relatively little research has been done on turbulent boundary layers in the presence of transverse curvature. In this paper transverse curvature denotes curvature in a plane normal to the flow direction as shown in Fig. 1. In particular, flow along the outside of cylinders is considered.In most of the experimental and theoretical investigations of the cylindrical boundary layers (see for example references 1 to 4) the effect of transverse curvature on the velocity profile, especially on the power law, was not considered. Exceptions to the above statement are Rao's inference on the velocity profile and Bonsignore's prediction of change in the index of the power law.

A Wind Driven Lake Circulation Finite Element Model for the Upper St. Marys River

Hydraulic Engineering, 1994

The hydrodynamics of the Upper St. Marys River is simulated by a three dimensional steady state f... more The hydrodynamics of the Upper St. Marys River is simulated by a three dimensional steady state finite element model. The rigid lid and hydrostatic pressure assumptions are used in the development of the model. The model is designed to study wind induced current circulation in large bodies of water. Some of the model features include the use of upwinding finite element, modifications to allow for bottom slip and inflows/outflows at the boundaries. The model uses triangle elements which can accurately represent the geometry of the study area. Due to its quick computation speed for current circulation dynamics under different wind and inflow/outflows conditions, a fine grid discretization is used on the Upper St. Marys River. The model was calibrated and verified using aerial photographs of the area and as well as current meter data from the U.S. Army Corps of Engineers, the Ontario Ministry of the Environment and from the firm of Integrated Exploration Limited.

$Research paper thumbnail of A fractional two-step implicit algorithm using curvilinear collected grids$

International Journal for Numerical Methods in Fluids, 2006

An e cient fractional two-step implicit algorithm is reported to simulate incompressible uid ows ... more An e cient fractional two-step implicit algorithm is reported to simulate incompressible uid ows in a boundary-ÿtted curvilinear collocated grid system. Using the ÿnite volume method, the convection terms are discretized by the high-accuracy Roe's scheme to minimize numerical di usion. An implicitness coe cient is introduced to accelerate the rate of convergence. It is demonstrated that the proposed algorithm links the fractional step method to the pressure correction procedure, and the SIMPLEC method could be considered as a special case of the fractional two-step implicit algorithm (when = 1). The proposed algorithm is applicable to unsteady ows and steady ows. Three benchmark twodimensional laminar ows are tested to evaluate the performance of the proposed algorithm. Performance is measured by sensitivity analyses of the e ciency, accuracy, grid density, grid skewness and Reynolds number on the solutions. Results show that the model is e cient and robust.

Closure of "Modeling of Rectangular Settling Tanks

Journal of Hydraulic Engineering, Feb 1, 1994

Shop ASCE; MyASCE; Donate Now; Contact Us; About Civil Engineering; About ASCE. ASCE Join Now. Kn... more Shop ASCE; MyASCE; Donate Now; Contact Us; About Civil Engineering; About ASCE. ASCE Join Now. Knowledge & Learning: Books & Journals; CE Body of Knowledge; Certification; Codes & Standards; Conferences; Continuing ...

Experimental Study of Flow in Setting Tanks

Journal of Environmental Engineering, Oct 1, 1988

An experimental study is reported of the effect of geometry on the hydraulics of rectangular sett... more An experimental study is reported of the effect of geometry on the hydraulics of rectangular settling tanks in the absence of density currents and suspended solids. A scale model that could be operated under various flows and geometric conditions was used in the investigation, and 13 configurations were tested using a laser-Doppler anemometer to measure the mean and rms velocities throughout th tank. The effects of tank length, inlet opening, and flow rate on velocity and turbulence distribution within the tank were studied. Flow patterns were obtained that showed the size of eddies, extent of the potential core, and the growth of the boundary layer. The energy balance was investigated on the basis of the measured velocities and depths. Mean kinetic energy and turbulent kinetic energy values were estimated integrating the mean velocity and rms profiles. All experiments were run with constant fluid density.