On the upstream mobility scheme for two-phase flow in porous media     

Siddhartha Mishra  Jérôme Jaffré 《Computational Geosciences》2010,14(1):105-124

When neglecting capillarity, two-phase incompressible flow in porous media is modelled as a scalar nonlinear hyperbolic conservation law. A change in the rock type results in a change of the flux function. Discretising in one dimension with a finite volume method, we investigate two numerical fluxes, an extension of the Godunov flux and the upstream mobility flux, the latter being widely used in hydrogeology and petroleum engineering. Then, in the case of a changing rock type, one can give examples when the upstream mobility flux does not give the right answer.  相似文献   

The evolution of the Palim granite in the Bastar tin province, Central India   总被引：1，自引：0，他引：1  

N. Pal  D. C. Pal  B. Mishra  F. M. Meyer 《Mineralogy and Petrology》2001,72(4):281-304

Summary The Palim granite, hosted by the metasedimentary country rocks in the Bastar tin province, is a heterogeneous pluton that comprises hornblende granite, biotite granite and two-mica granite. Spherical inhomogeneous surmicaceous enclaves occur within the granites with coarse grained cores of muscovite mantled by finer muscovite-quartz-biotite (± sillimanite) rims. Geochemical features imply that the granites are highly evolved and geochemically distinct. Petrographic and geochemical considerations point towards a transition from metaluminous I-type hornblende-bearing granite in the south to peraluminous volatile-enriched S-type like lithologies (biotite and two-mica granites) towards north. Modeling of highly incompatible elements such as Nb and Cs, implies 31 to 33% assimilated fractional crystallization of a melt with an initial composition close to that of the hornblende granite to form the two-mica granite. Hornblende geobarometry, plagioclase-hornblende thermometry (in hornblende granite) and phengite barometry (in two-mica granite), yield P-T estimates of 5–7 kb/725°–760 °C, and 6 kb/700 °C, respectively. The study further implies that a genetic link exists between granite magmatism and the formation of tin pegmatites in the region. The preponderance of peripheral pegmatites to the north-east of the Palim granite is regarded a result of outward crystal-melt fractionation and tectonic tilting of the pluton. Received October 21, 1999; revised version accepted December 12, 2000  相似文献   

Channel form and processes of the flood-dominated Narmada River,India     

S. N. Rajaguru  Avijit Gupta  V. S. Kale  Sheila Mishra  R. K. Ganjoo  L. L. Ely  Yahouda Enzel  V. R. Baker 《地球表面变化过程与地形》1995,20(5):407-421

The 1300 km long Narmada River flows along a structural lineament, alternating between constricting rocky gorges and rapids, and meandering wide alluvial reaches. Channel forms and processes were studied in a 120 km long section of an alluvial reach. Channel size, shape and bedforms in the Narmada River are related to very large floods which have occurred three times in this century. During such floods the entire 400 m wide channel is utilized and 10–15 m high cliffs on both sides operate as riverbanks. Normally, even the high flows of the south-western monsoon are insufficient to fill the whole channel, and hence their effects are limited to building of discontinuous floodplains between the cliffs and modifying bedforms and bars. A channel-in-channel topography is thus created. The very large floods are also responsible for erosion of the rocky stretches and building of point bars. The river meanders, but its movement is restricted because of (1) rocky gorges and scablands operating as anchor points at intervals, and (2) the presence of high alluvial cliffs which are topped on extremely rare occasions. In spite of being located in a tectonically active zone in a monsoon setting, it is the exceptional high-magnitude floods at irregular intervals which control the form and behaviour of the Narmada River.  相似文献   

An analytic representation of the three-dimensional structure of monsoon depressions     

S. K. Mishra  D. R. Chakraborty  S. S. Desai 《Meteorology and Atmospheric Physics》1982,31(4):329-337

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Some analytical vertical profiles of monsoonal zonal wind over India     

S. K. Mishra 《Meteorology and Atmospheric Physics》1980,29(1-2):109-117

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Electrokinetic properties and flotation behaviour of apatite and calcite in the presence of sodium oleate and sodium metasilicate     

S.K. Mishra 《International Journal of Mineral Processing》1982,9(1):59-73

Calcite is generally associated with apatite minerals in phosphate deposits. To explore the possibility of separating these minerals by a soap flotation technique, their electrokinetic properties and flotation behaviour were studied in the presence of sodium oleate.Microelectrophoresis data indicate oleate adsorption on these minerals, and from Hallimond-tube flotation tests it has been noted that in a controlled pH environment and for a certain sodium oleate concentration range, separation of these minerals is possible.The study of apatite/calcite-sodium metasilicate-sodium oleate systems indicates the preferential adsorption of silicate at the calcite surface. This suggests the potential use of sodium metasilicate as the modifying agent for the separation of apatite from calcite by depressing calcite when using sodium oleate as collector.  相似文献   

On the propagation of wave from a cylindrical cavity     

D. M. Mishra  A. K. Das 《Pure and Applied Geophysics》1970,78(1):96-99

Summary This paper discusses the disturbance produced in an infinite layer of non-homogeneous elastic material characterised by =0 ⁿ and =0ⁿ(n>0) where and are the density and shear modulus respectively of the material, due to periodic torsional force applied on the wall of a cylindrical hole in the layer. The variation of the displacement component with the radius vector is shown graphically and compared with the corresponding homogeneous case.  相似文献   

Contribution of baroclinic mechanism in the formation of the depression during MONEX-79     

P. S. Salvekar  L. George  S. K. Mishra 《Meteorology and Atmospheric Physics》1983,32(1-2):55-69

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Epigenetic Nature of the BIF-hosted Gold Mineralization at Ajjanahalli, Southern India: Evidence from Ore Petrography and Fluid Inclusion Studies: Reply     

Nabarun Pal  Biswajit Mishra   《Gondwana Research》2004,7(2):632-635

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Drought forecasting using stochastic models   总被引：8，自引：4，他引：8  

A. K. Mishra  V. R. Desai 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(5):326-339

Drought is a global phenomenon that occurs virtually in all landscapes causing significant damage both in natural environment and in human lives. Due to the random nature of contributing factors, occurrence and severity of droughts can be treated as stochastic in nature. Early indication of possible drought can help to set out drought mitigation strategies and measures in advance. Therefore drought forecasting plays an important role in the planning and management of water resource systems. In this study, linear stochastic models known as ARIMA and multiplicative Seasonal Autoregressive Integrated Moving Average (SARIMA) models were used to forecast droughts based on the procedure of model development. The models were applied to forecast droughts using standardized precipitation index (SPI) series in the Kansabati river basin in India, which lies in the Purulia district of West Bengal state in eastern India. The predicted results using the best models were compared with the observed data. The predicted results show reasonably good agreement with the actual data, 1–2 months ahead. The predicted value decreases with increase in lead-time. So the models can be used to forecast droughts up to 2 months of lead-time with reasonably accuracy.  相似文献