1,508 research outputs found
Splash wave and crown breakup after disc impact on a liquid surface
In this paper we analyze the impact of a circular disc on a free surface
using experiments, potential flow numerical simulations and theory. We focus
our attention both on the study of the generation and possible breakup of the
splash wave created after the impact and on the calculation of the force on the
disc. We have experimentally found that drops are only ejected from the rim
located at the top part of the splash --giving rise to what is known as the
crown splash-- if the impact Weber number exceeds a threshold value
\Weber_{crit}\simeq 140. We explain this threshold by defining a local Bond
number based on the rim deceleration and its radius of curvature,
with which we show using both numerical simulations and experiments that a
crown splash only occurs when , revealing that the rim
disrupts due to a Rayleigh-Taylor instability. Neglecting the effect of air, we
show that the flow in the region close to the disc edge possesses a
Weber-number-dependent self-similar structure for every Weber number. From this
we demonstrate that \Bond_{tip}\propto\Weber, explaining both why the
transition to crown splash can be characterized in terms of the impact Weber
number and why this transition occurs for .
Next, including the effect of air, we have developed a theory which predicts
the time-varying thickness of the very thin air cushion that is entrapped
between the impacting solid and the liquid. Our analysis reveals that gas
critically affect the velocity of propagation of the splash wave as well as the
time-varying force on the disc, . The existence of the air layer also
limits the range of times in which the self-similar solution is valid and,
accordingly, the maximum deceleration experienced by the liquid rim, what sets
the length scale of the splash drops ejected when We>\Weber_{crit}
Air Pollution In India – Causes, Effects And Solutions
Air is the necessary for the very existence of human beings, animals and plants that appeared on the earth. However, due to the rapid growth of population and technology the air was polluted day by day. In 2011, India’s Central Pollution Control Board had presented the report according to which 180 cities in India had particulate matter six times more than the permissible limit set by the World Health Organization in the air. Vehicles, biomass burning, fuel tarnishing are few of the major causes of air pollution in India. The problem of air pollution is so big that we cannot manage to pay for overlook it. As such it has to be handled with a high degree of care. This paper focuses on causes, effects of air pollutions in India and steps to solve the problems and policy measures to ensure reduce air pollution to the entire resident of earth. This study mainly descriptive in nature and secondary data are used for the purpose of the study. The data was collected from books, various articles, journals and websites
Exploring droplet impact near a millimetre-sized hole: comparing a closed pit with an open-ended pore
We investigate drop impact dynamics near both closed pits and open- ended
pores experimentally. The resulting impact phenomena differ greatly for a pit
or a pore. For the first, we observe three phenomena: a splash, a jet and an
air bubble, whose appearance depends on the distance between impact location
and pit. Furthermore, we found that splash velocities can reach up to seven
times the impact velocity. Drop impact near a pore, however, results solely in
splashing. Surprisingly, two distinct and disconnected splashing regimes occur,
with a region of plain spreading in-between. For pores, splashes are less
pronounced than in the pit case. We state that, for the pit case, the presence
of air inside the pit plays a crucial role: it promotes splashing and allows
for air bubbles to appear.Comment: 17 pages, 11 figures, 1 supplementary movie, submitted to JF
Temperature dependence of pure quadrupole resonance of 35Cl in α-CH2ClCOOH
Measurements of the pure quadrupole resonance frequency of 35Cl in CH2ClCOOH have been made over a wide range of temperature (77K to 300K). Two resonance lines due to chemically inequivalent sites have been observed throughout the above temperature range
Technoeconomic assessment of marine fish production, marketing and capacity utilization of processing plants in Gujarat
Among the major maritime states of India,
Gujarat has the longest coastline (1,600 km) and
the largest continental shelf area (1,65,00
sq.km). The current annual catch of marine fish
in this state is 6,45,261 tonnes (1994-'95). landed
in about 221 coastal fish landing centres by
21,018 fishing units, manned by about 0.75 lakh
fishermen
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