Study Area: Bangalore

About

Bangalore, capital city of Karnataka is the sixth largest metropolis in the country and a nerve center for the various cultural, social and religious activities, contributing to the growth of the city. Bangalore district is situated in the heart of the South-Deccan plateau in peninsular India to the South-Eastern corner of Karnataka State between the latitudinal parallels of 12°39' N & 13°18' N and longitudinal meridians of 77°22' E & 77°52'E at an altitude of about 3000 ft. above sea level covering an area of approximately 800 sq. kms. The temperature varies from a minimum of 14°C to a maximum of 33°C and Rainfall (Actual) of about 1060 mm. The pleasant weather has the warmest months from March to May, coldest months from December to January, rainy - southwest monsoon from June to September and rainy - northeast monsoon from November to December.

Bruhat Bangaluru Mahanagara Palike (BBMP Area) has a total of 198 wards spread across the 4 taluks namely, Bangalore North, Bangalore South, Bangalore East and Anekal. It is also categorised into zones namely, Byatarayanapura Zone,Dasarahalli Zone, Rajarajeshwarinagar Zone, South Core Zone, West Core Zone, East Core Zone, Bommanahalli Zone and Mahadevapura Zone, as shown in Figure1.

The present study area is located in Bangalore South Taluk and belongs to Bommanahalli Zone (Figure 2). It contains two watershed, namely Hulimavu kere watershed and Madivala Kere watershed, as shown in Figure 3.

The study area has the following lakes in its catchment area:

• Gottigere Kere
• Hulimavu Kere
• Madivala Kere
• Are kere
• Meenakshi kere
• Nyanappanahalli Kere
• Subbarayana Kere
• Yelanahalli Kere
• Kalena Agrahara Kere

Laboratory Setup

The upstream section of Madivala Kere is modelled in the Experimental Laboratory Setup. Total storm runoff of Are Kere catchment, Hulimavu Kere catchment and Gottigere catchment contributes to Madiwala Kere catchment, which has high turbulent flow and gravity flow, the schematic representation of which is shown in Figure 4.

The flow analysis in prototype (BH554) is carried out using Experimental data obtained from model and Numerical(CFD) flow analysis. The experimental model results are converted into prototype by using scale ratio parameter

The scaled model (Figure 5) is consisting of a rectangular Drain of length 10 m, width 0.5 m and height 0.61m. The rectangular Drain is of tilting type. A tank and a reservoir arrangement are provided for re-circulation of water in the Drain. Two baffles are provided in the tank in order to minimise unsteadiness of water. In order to prevent flow separation, curvature is provided in the tank near the Drain approach. From the Drain, water finally drains in the reservoir located at extreme end of the Drain. The water is again fed to the tank with the help of a 0.1 m diameter delivery pipe. A 15 HP centrifugal pump is used for delivery in the pipe. The flow rate is regulated by means of a valve located on the delivery line. A sharp-edged orifice meter is installed in the delivery line. For the orifice, standard D-D/2 taping are used for pressure drop measurements. A mercury-water manometer (Figure 6a) is provided for pressure drop measurement across the orifice. An Acoustic Doppler's Velocitimeter (Figure 6b) and Ultrasonic Water Level Sensor (Figure 6c) has been used to compute the velocity variations, water level measurements respectively

Froudian model is developed for the present study. Distorted scale models typically have a vertical scale that is exaggerated with respect to the horizontal scale to allow sufficient depth to produce turbulent flow and permit stratified flow visualization. The kinematic viscosity can’t be scaled down, and hence same Reynolds number can’t be maintained. In our case study, the vertical length scale ratio YR is 6.4 and horizontal scale ratio XR is 13.5 is considered. By scaling down the laboratory parameters obtained are as follows. The experiments can be done for different discharges, by changing the YR scale ratio.

INSTRUMENTS USED IN THE LAB SETUP

VALIDATION CFD MODEL WITH EXPERIMENTS RESULTS

The Numerical (CFD) model is validated using Experimental data from laboratory drain model. The experimental data is collected at distance 5m from the upstream end of drain. The velocity profile and flow depth are measured with respective time of the experiment. Velocity is measured by 3D acoustic Doppler velocimeters (Figure 6b), it is measured in x direction with respective time of flow. Flow depth profile measured using ultrasonic level sensor (Figure 6c) with respective time of flow. To validate experimental result with numerical result similar geometry is prepared in Flow 3D. (Figure7a and 7b)

Experimental and CFD study of flow in laboratory are done for the following cases:

Experimental study of flow in Horizontal bed

Flow analysis in drain without obstruction

Flow analysis in drain with obstruction

Flow analysis in drain with 60% blockage

Flow analysis in Drain with bridge obstruction

Flow analysis in the drain with different percentage of opening

Flow analysis in the Drain with plant obstruction

Flow in the Drain with gate operation

Flow in Drain with bottle obstruction

Experimental study of flow in sloping Drain

Flow in Drain with 60% obstruction

Flow in Drain with 80% obstruction

Flow in Drain with bridge obstruction

Flow in Drain with plant obstruction

Hydrological analysis of data in SWMM

Validation of CFD Drain model with SWMM hydrological data

Flow in Drain (BH554) with 10% obstruction

Flow in Drain (BH554) with 20% obstruction

Flow in Drain (BH554) with 30% obstruction

Flow in Drain (BH554) with 40% obstruction

Flow in Drain (BH554) with 50% obstruction

Flow in Drain (BH554) with 60% obstruction

Flow in Drain (BH554) with 70% obstruction