Department of Civil & Infrastructure Engineering

&ldquo;IIT Jodhpur is committed to impart quality education to facilitate the creation of qualified, competent and responsible human resources to meet the emerging technological challenges of the world. It is working towards creating an equitable learning platform that is positive, accessible and effective in the face of the modern societal and scientific advancements.

Flexibility in curriculum, in all its academic programs, encompassing elements of teaching, research, creativity, innovation and entrepreneurship is the most unique feature of IIT Jodhpur. The Department of Science and Technology (DST), under the National Mission on Cyber Physical Systems, has identified IIT Jodhpur as a Technology &amp; Innovation Hub in the area of Augmented Reality and Virtual Reality. The institute has also been nominated as the coordinator for the Jodhpur City and Knowledge Cluster by the Office of Principal Scientific Adviser, Government of India.

The sprawling 852-acre IIT Jodhpur campus is a majestic tribute to the deep-rooted diverse cultural heritage of the region. The campus is an architectural masterpiece, which is slated to become an international exemplar of sustainability with net-zero energy, and advanced water and waste management strategies.&rdquo;

IIT Jodhpur

This paper presents the findings of an experimental study on the three-dimensional turbulent flow field in the vicinity of a rectangular cross-section cylinder placed at the sidewall of a rectangular open channel. Uniform sand of median diameter 0.52 mm was glued over the channel bottom to make it rough. Detailed measurements of the time-averaged velocity components, turbulent intensity components, turbulent kinetic energy and Reynolds stresses were taken by the acoustic doppler velocimeter (ADV) at different vertical sections around the cylinder. In the upstream, presentation of flow fields through vectors at vertical and horizontal sections show a primary vortex associated with the downflow near the cylinder. On the other hand, in the downstream, the flow field shows a three-dimensional separated flow with vortex shedding. Using the Reynolds stresses and velocity gradients, the bed shear stresses are determined. In front of the cylinder, the velocity and the bed shear stress are found to be approximately 1.6 and 3.3 times of their magnitudes at free flow upstream zone, respectively. The data presented in this paper would be useful to the investigators for the development and verification of mathematical models of flow field in the vicinity of vertical-wall abutments. © 2004 Elsevier Ltd. All rights reserved.

World University root node

Flow Measurement and Instrumentation

Turbulent flow measurement by the ADV in the vicinity of a rectangular cross-section cylinder placed at a channel sidewall

The paper presents the application of artificial neural network (ANN) to determine the end-depth-ratio (EDR) for a smooth inverted semicircular channel in all flow regimes (subcritical and supercritical). The experimental data were used to train and validate the network. In subcritical flow, the end depth is related to the critical depth, and the value of EDR is found to be 0.705 for a critical depth-diameter ratio up to 0.40, which agrees closely with the value of 0.695 given by Dey [Flow Meas. Instrum. 12 (4) (2001) 253]. On the other hand, in supercritical flow, the empirical relationships for EDR and non-dimensional discharge with the non-dimensional streamwise slope of the channel are established. © 2004 Elsevier Ltd. All rights reserved.

End depth computation in inverted semicircular channels using ANNs

The flow upstream of a free overfall from smooth inverted semicircular channels is theoretically analysed to compute the end-depth ratio (EDR), applying an energy equation based on the Boussinesq assumption. This approach eliminates the need for an experimentally determined pressure coefficient. Experiments were conducted with horizontal channel conditions. The EDR related to the critical depth, which occurs upstream from the end section, is found to be around 0.695 for a critical depth-diameter ratio up to 0.40. A simple method is presented to estimate the discharge from a known end-depth. The theoretical model corresponds closely with the experimental data.

Nordic Hydrology

End-depth in inverted semicircular channels: Experimental and theoretical studies

Theoretical and experimental investigations are presented on the threshold of noncohesive sediment motion under a steady-uniform stream flow on a combined transverse (across the flow direction) and longitudinal (streamwise direction) sloping bed. Theoretical analysis of the equilibrium of a sediment particle lying on a combined transverse and longitudinal sloping bed shows that the critical shear stress ratio (ratio of critical shear stress for a sloping bed to that for a horizontal bed) is a function of the transverse bed slope, longitudinal bed slope, angle-of-repose of sediment particles and lift-drag ratio. As in laboratory flume study, the uniform flow is difficult to establish in a steeply sloping channel and is impossible to obtain in an adversely sloping channel, experiments were conducted in two inverted semicircular ducts (closed-conduit flow) for three sizes of uniform sediments. The critical shear stresses for experimental runs were determined considering side-wall correction. The experimental results correspond closely with the results obtained using the present model. The model can be applicable to both the channel beds and banks.

Journal of Hydraulic Research

Threshold of sediment motion on combined transverse and longitudinal sloping beds [Seuil de mise en mouvement des sédiments sur des lits de pente transversale et longitudinale]

A model is presented to determine the critical shear stress for the incipient motion of bivalve shells on a horizontal sand bed, under a unidirectional flow of water. Hydrodynamic forces on a solitary bivalve shell, resting over a sand bed, are analyzed for the condition of incipient motion including the effect of turbulent fluctuations. Hydrodynamic forces such as drag and lift are taken into consideration. Three types of bivalve shells, namely Coquina Clam, Cross-barred Chione and Ponderous Ark, were tested experimentally for the condition of incipient motion. The shape parameter of bivalve shells is defined appropriately. Experiments were conducted in a flume with a horizontal bed, and the critical shear stresses were computed using Vanoni's side-wall correction. The experimental data are used to calibrate the model making lift coefficient a free parameter. The results obtained using the present model agree satisfactorily with the experimental data.

Journal of Engineering Mechanics

Incipient motion of bivalve shells on sand beds under flowing water

This paper presents a theoretical and experimental study on free overfall in a smooth inverted semicircular channel. Applying the momentum equation based on the Boussinesq approximation, the flow upstream of a free overfall is theoretically analyzed to calculate the end-depth-ratio (EDR). This approach eliminates the need of an empirical pressure coefficient. In subcritical flows, the EDR related to the critical depth is found to be 0.705 for critical depth-diameter ratio up to 0.42. In supercritical flows, the Manning equation is used to express the end-depth as a function of the streamwise slope of the channel. Methods to estimate discharge from the end-depth in subcritical and supercritical flows are presented. The discharge is also related to the end-depth and a characteristic parameter of the channel. The upstream free surface profiles are computed using the streamline curvature at free surface. The computed and experimental results are in satisfactory agreement in subcritical flow and have a slight discrepancy in supercritical flow.

Journal of Hydraulic Engineering

Free overfall in inverted semicircular channels

Free overfall in U-shaped channels is theoretically analyzed, applying a momentum equation based on the Boussinesq approximation, to obtain the equation of end depth. The end-depth ratio is 0.75 up to normalized critical depth 0.50; and then it decreases gradually with an increase in normalized critical depth. A method to estimate discharge from the end depth is presented. The upstream flow profile of a free overfall is computed using the streamline curvature at the free surface. Experiments were conducted in two U-shaped channels to verify the model. The results obtained using the model agree satisfactorily with the experimental data.

Overfall in U-shaped channels

The results of an experimental investigation of the time variation of scour hole and the flow characteristics of the quasi-equilibrium state of scour of a cohesive bed downstream of an apron due to a submerged horizontal jet issuing from a sluice opening are presented. Experiments were carried out with natural cohesive sediment for various sluice openings, jet velocities, and lengths of apron. Attempts are made to explain the similarity existing either in the process of scour or in the scour profiles that the scour holes follow downstream of an apron. The scour profiles at different times follow a particular geometrical similarity and can be expressed by a polynomial using relevant parameters. The characteristics parameters affecting the time variation of scour depth are identified based on the physical reasoning and dimensional analysis. An equation for time variation of maximum scour depth is obtained empirically. The diffusion characteristics of the submerged jet, growth of boundary layer thickness, velocity distribution within the boundary layer, and shear stress at the quasi-equilibrium state of scour are also investigated. The expression of shear stress is obtained from the solution of the von Kármán momentum integral equation.

Hydraulics of submerged jet subject to change in cohesive bed geometry

Journal of Irrigation and Drainage Engineering

Closure to “edr in circular channels”

A free overfall at the end of an open channel offers a simple means of measuring flow discharge. In this paper, two methods are presented for the computation of end-depth and discharge of a free overfall from smooth circular channels with flat base. Firstly, applying the momentum equation based on the Boussinesq approximation, the flow upstream of a free overfall is theoretically analyzed to calculate the end-depth-ratio (EDR). This approach eliminates the need of an experimentally determined pressure coefficient. In subcritical flows, the EDR is related to the critical-depth that occurs far upstream. In supercritical flows, the Manning equation is used to express the end-depth as a function of streamwise slope of the channel. Methods to estimate discharge from the end-depth in subcritical and supercritical flows are presented. The upstream flow profiles of a free overfall are computed using the streamline curvature at free surface. Secondly, an alternate method for analyzing free overfall from circular channels with flat base is also presented, where a free overfall in a circular channel with flat base is simulated by the flow over a sharp-crested weir to calculate the EDR. The comparisons of the computed results with the experimental data are satisfactory for subcritical flow and acceptable for supercritical flow. © 2002 Elsevier Science Ltd. All rights reserved.