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 12o39' N & 13o18' N and longitudinal meridians of 77o22' E & 77o 52'E at an altitude of about 3000ft. above sea level covering an area of 2,190 sq. kms. The temperature varies from a minimum of 14oC to a maximum of 33oC 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.

Bangalore 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.

The present study area is located in Bangalore South Taluk and belongs to Bommanahalli Zone. It contains two watershed, namely Hulimavu kere watershed and Madivala Kere watershed.

 

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 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 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 minimize 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 tapings are used for pressure drop measurements. A mercury-water manometer is provided for pressure drop measurement across the orifice.

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.

Dynamic Similarity between Prototype and Model
                 

 

INSTRUMENT USED IN PROJECT

Mercury manometer

Acoustic Doppler Velocimeters (ADV)

Ultrasonic level sensor

 

 

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, it is measured in x direction with respective time of flow. Flow depth profile measured using ultrasonic level sensor with respective time of flow. To validate experimental result with numerical result similar geometry is prepared in Flow 3D

 

Flow 3D geometry

a)      Drain geometry and Grit generation

b)      Boundary condition

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