Abstract: Present study was aimed to develop a discharge
measuring device for irrigation and laboratory channels. Experiments
were conducted on sharp edged constricted flow meters having four
types of width constrictions namely 2:1, 1.5:1, 1:1 and 90o in the
direction of flow. These devices were made of MS sheets and
installed separately in a rectangular flume. All these four devices
were tested under free and submerged flow conditions. Eight
different discharges varying from 2 lit/sec to 30 lit/sec were passed
through each device. In total around 500 observations of upstream
and downstream depths were taken in the present work. For each
discharge, free submerged and critical submergence under different
flow conditions were noted and plotted. Once the upstream and
downstream depths of flow over any of the device are known, the
discharge can be easily calculated with the help of the curves
developed for free and submerged flow conditions. The device
having contraction 2:1 is the most efficient one as it allows maximum
critical submergence.
Abstract: For many chemical and biological processes, the understanding of the mixing phenomenon and flow behavior in a stirred tank is of major importance. A three-dimensional numerical study was performed using the software Fluent, to study the flow field in a stirred tank with a Rushton turbine. In this work, we first studied the flow generated in the tank with a Rushton turbine. Then, we studied the effect of the variation of turbine’s submergence on the thermodynamic quantities defining the flow field. For that, four submergences were considered, while maintaining the same rotational speed (N =250rpm). This work intends to optimize the aeration performances of a Rushton turbine in a stirred tank.
Abstract: In this study an extensive experimental research is
carried out to develop a better understanding of the effects of Piano Key (PK) weir geometry on weir flow threshold submergence.
Experiments were conducted in a 12 m long, 0.4 m wide and 0.7 m deep rectangular glass wall flume. The main objectives were to
investigate the effect of the PK weir geometries including the weir
length, weir height, inlet-outlet key widths, upstream and
downstream apex overhangs, and slopped floors on threshold submergence and study the hydraulic flow characteristics. From the
experimental results, a practical formula is proposed to evaluate the flow threshold submergence over PK weirs.
Abstract: The paper presents the results of a series of
experiments conducted on physical models of Quarter-circle
breakwater (QBW) in a two dimensional monochromatic wave
flume. The purpose of the experiments was to evaluate the reflection
coefficient Kr of QBW models of different radii (R) for different
submergence ratios (d/hc), where d is the depth of water and hc is the
height of the breakwater crest from the sea bed. The radii of the
breakwater models studied were 20cm, 22.5cm, 25cm, 27.5cm and
submergence ratios used varied from 1.067 to 1.667. The wave
climate off the Mangalore coast was used for arriving at the various
model wave parameters. The incident wave heights (Hi) used in the
flume varied from 3 to 18cm, and wave periods (T) ranged from 1.2 s
to 2.2 s. The water depths (d) of 40cm, 45cm and 50cm were used in
the experiments. The data collected was analyzed to compute
variation of reflection coefficient Kr=Hr/Hi (where Hr=reflected wave
height) with the wave steepness Hi/gT2 for various R/Hi
(R=breakwater radius) values. It was found that the reflection
coefficient increased as incident wave steepness increased. Also as
wave height decreases reflection coefficient decreases and as
structure radius R increased Kr decreased slightly.
Abstract: The effects of global warming on India vary from the
submergence of low-lying islands and coastal lands to the melting of
glaciers in the Indian Himalayas, threatening the volumetric flow rate
of many of the most important rivers of India and South Asia. In
India, such effects are projected to impact millions of lives. As a
result of ongoing climate change, the climate of India has become
increasingly volatile over the past several decades; this trend is
expected to continue.
Climate change is one of the most important global environmental
challenges, with implications for food production, water supply,
health, energy, etc. Addressing climate change requires a good
scientific understanding as well as coordinated action at national and
global level. The climate change issue is part of the larger challenge
of sustainable development. As a result, climate policies can be more
effective when consistently embedded within broader strategies
designed to make national and regional development paths more
sustainable. The impact of climate variability and change, climate
policy responses, and associated socio-economic development will
affect the ability of countries to achieve sustainable development
goals.
A very well calibrated Soil and Water Assessment Tool (R2 =
0.9968, NSE = 0.91) was exercised over the Khatra sub basin of the
Kangsabati River watershed in Bankura district of West Bengal,
India, in order to evaluate projected parameters for agricultural
activities. Evapotranspiration, Transmission Losses, Potential
Evapotranspiration and Lateral Flow to reach are evaluated from the
years 2041-2050 in order to generate a picture for sustainable
development of the river basin and its inhabitants.
India has a significant stake in scientific advancement as well as
an international understanding to promote mitigation and adaptation.
This requires improved scientific understanding, capacity building,
networking and broad consultation processes. This paper is a
commitment towards the planning, management and development of
the water resources of the Kangsabati River by presenting detailed
future scenarios of the Kangsabati river basin, Khatra sub basin, over
the mentioned time period.
India-s economy and societal infrastructures are finely tuned to the
remarkable stability of the Indian monsoon, with the consequence
that vulnerability to small changes in monsoon rainfall is very high.
In 2002 the monsoon rains failed during July, causing profound loss
of agricultural production with a drop of over 3% in India-s GDP.
Neither the prolonged break in the monsoon nor the seasonal rainfall
deficit was predicted. While the general features of monsoon
variability and change are fairly well-documented, the causal
mechanisms and the role of regional ecosystems in modulating the
changes are still not clear. Current climate models are very poor at
modelling the Asian monsoon: this is a challenging and critical
region where the ocean, atmosphere, land surface and mountains all
interact. The impact of climate change on regional ecosystems is
likewise unknown. The potential for the monsoon to become more
volatile has major implications for India itself and for economies
worldwide. Knowledge of future variability of the monsoon system,
particularly in the context of global climate change, is of great
concern for regional water and food security.
The major findings of this paper were that of all the chosen
projected parameters, transmission losses, soil water content,
potential evapotranspiration, evapotranspiration and lateral flow to
reach, display an increasing trend over the time period of years 2041-
2050.