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1
Content available remote Stability of stratified Oldroydian fluid in hydromagnetics in presence of suspended particle in porous medium
100%
Singh V. , Dixit S.
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tom Vol. 32, nr 4
55-65
EN
In the present note, the stability of stratified Oldroyd viscoelastic fluid in the presence of suspended particles and variable magnetic field in porous medium has been studied. The case of exponentially varying density, viscosity, magnetic field and suspended particles is considered. The system is found to be unstable for the disturbances of all wave numbers for potentially unstable stratification. The effect of variable horizontal, magnetic field has been discussed in the note. The growth rate decreases or increases with the increase in particle density and kinematic viscosity; similarly, the growth rate increases or decreases with an increase in medium permeability and strain retardation time.
2
Content available remote Effect of the magnetic field and suspended particles on thermosolutal instability of a rotating Rivlin-Ericksen fluid with varying gravity field in a porous medium
100%
Singh V. , Dixit S.
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2012
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tom Vol. 17, no. 2
559-570
EN
In the paper we consider thermal instability of a rotating Rivlin-Ericksen viscoelastic fluid in the presence of suspended particles in a porous medium, the effect of magnetic field with varying gravity field are also studied. It is found that for stationary convection, a Rivlin-Ericksen fluid behaves like an ordinary Newtonian fluid while the magnetic field has both stabilizing and destabilizing effect on the system. Other different aspects affecting stability are also considered.
3
Content available remote Thermosolutal convection in Rivlin-Ericksen fluid in the presence of Hall currents in a porous medium in hydromagnetics
100%
Kango S. K. , Singh V.
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2012
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tom Vol. 17, no. 1
71-82
EN
The thermosolutal instability of a layer of a Rivlin-Ericksen elastico-viscous fluid is considered in the presence of a uniform horizontal magnetic field to include the Hall currents in a porous medium. For the case of stationary convection, the Hall currents hasten the onset of convection, the magnetic field postpones the onset of convection, medium permeability also postpones the onset of convection in the presence of the Hall currents, whereas the kinematic viscoelasticity has no effect on the onset of convection. The Hall currents, kinematic viscoelasticity, magnetic field, medium permeability and the solute parameter introduce oscillatory modes in the system, which were non-existent in their absence. The case of overstability is also considered wherein the sufficient conditions for the non-existence of overstability are obtained.
4
SCS-CN method. Part II: Analytical treatment
100%
Mishra S. , Singh V.
Acta Geophysica Polonica
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2003
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tom Vol. 51, nr 1
107-123
EN
This part of the paper, a sequel to Part I, in continuation of the analytical treatment of the Soil Conservation Service curve number (SCS-CN) method, further explores the SCS-CN method for: Z(a) its functional behaviour, (b) the physical interpretation of its proportional equality and curve number, (c) the derivation of seldom explored potential macimum retention S-CN relation, and (d) the development of CN-antecedent moisture condition (AMC) relations. Finally, an attempt is made to present the SCS-CN concept as a viable alternative to power law.
5
Derivation of the SCS-CN parameter S from linearized Fokker-Planck equation
100%
Mishra S. , Singh V.
Acta Geophysica Polonica
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2003
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tom Vol. 51, nr 2
179-202
EN
The potential maximum retention, S, of the Soil Conservation Service Curve Number (SCS-CN) method (SCS, 1956) was derived for a large set of published infiltration data ranging from Plainfield sand to Yololight clay using the relations between psi (negative pressure) and theta (moisture content) and between K (hydraulic conductivity) and theta. The physical significance of S is explained using the diffusion term of the linearized, Fokker-Planck equation for infiltration, which relates S to the storage and transmission properties of the soil. The s-values exhibit a strong looped relationship with the initial moisture content, analogous to that for curve numbers for three antecedent moisture conditions. The variations of S in vertical infiltration is also explained and discussed.
6
Content available remote Effect of plasma on modal dispersion characteristics of elliptical Bragg waveguide
80%
Prajapati Y. , Saini J. P. , Chauhan D. S. , Singh V.
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2014
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tom Vol. 22, No. 1
16-23
EN
In this paper, the dispersion characteristics of a plasma filled elliptical Bragg waveguide is investigated. The modal characteristic equations of the proposed Bragg waveguide for both ω > ωp and ω < ω p are derived. The effects of plasma frequency, numbers of cladding layers and the eccentricity of elliptical Bragg waveguide on the dispersion characteristics are studied. The analysis shows that the introduction of plasma in the proposed waveguide allows to control the propagation of modes.
7
Content available Linear stability analysis for ferromagnetic fluids in the presence of magnetic field, compressibility, internal heat source and rotation through a porous medium
80%
Kumar K. , Singh V. , Sharma S.
Journal of Theoretical and Applied Mechanics
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2015
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tom Vol. 53 nr 4
1067--1081
EN
The effects of magnetic field and heat source strength on thermal convection of a compressible rotating ferromagnetic fluid through a porous medium are investigated theoretically using linear stability theory. A normal mode analysis method is employed to find solutions for the fluid layer confined between parallel planes with free boundaries. The cases of stationary and oscillatory instabilities are discussed. For the stationary state, compressibility, medium porosity and temperature gradient due to heat source have destabilizing effects, whereas rotation and ratio of magnetic permeability delay the onset of convection. The magnetic field and medium permeability have both stabilizing and destabilizing effects under certain conditions. The variations in the stationary critical thermal Rayleigh number and neutral instability curves in (Ra1, x)-plane for various values of physical parameters are shown graphically to depict the stability characteristics. The sufficient conditions for the non-existence of overstability are obtained and the principle of exchange of stabilities holds true in the absence of magnetic field and rotation under certain conditions.
8
Physics of flood frequency analysis. II. Convective diffusion model versus lognormal model
80%
Strupczewski W. , Singh V. , Węglarczyk S. , Mitosek H.
Acta Geophysica Polonica
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2003
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tom Vol. 51, nr 1
85-106
EN
The similarity between the convective diffusion (CD) model and the lognormal (LN) distribution is shown by comparison of their moment estimates. Both models are tested using annual peak discharges observed at 39 gauging-sections of Polish rivers. The average value of the ration of the coefficient of skew ness to the coefficient of variation equals about 2.52, a value closer to the ration of the CD model than to the gamma or the lognormal model. The likelihood ratio indicates the preference of the CD over the LN model for 27 out of 39 cases. Applying the maximum likelihood (ML) method, one should take into account the consequence of the wrong distributional assumption on the estimate of moments. In the case of CD, the ML-estimate of the means is unbiased for any true distribution, which is not the case with the LN model, moreover the ML-estimate of the two fist moments of CD remains asymptotically unbiased if LN is true, while there is small bias in the opposite case. To check the objectivity of our inferences from empirical findings, a simulation experiment was carried out, which comprised generated CD- and LN- distributed samples and both the moment and likelihood criteria for the distribution choice. Its results clearly show that normal hydrological sample sizes are far too small for selecting the true distribution.
9
Analyses of total magnetic anomalies over the northeastern marginal areas of Central India
80%
Singh V. , Singh O. , Agrawal B. , Shanker D.
Acta Geophysica Polonica
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2003
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tom Vol. 51, nr 2
165-177
EN
Detailed ground magnetic survey has been carried out with the station spacing of 2 to 5 km around Jabalpur-Mandala region. Stron magnetic anomalies are observed in the adjoining areas of Habalpur-Mandala and adjoining areas of Central India. The anomalies are generally closed and aligned in the E-W to NE-SW direction. Magnetic interpretation predicts an average thickness of 0.6 km for the Deccan traps, besides bringing out shallow and deeper intrusive boodies at 1.5 and 4.5 km, respectively. The average thickness of the trap is in good agreement with DSS (Deep Seismic Sounding) and magnetotelluric results. 2-D modeling along six profiles also suggests a number of sheet and dyke-like structures to be present in the region up to a depth of 4.7 km. It is inferred that many zones of weakness along the E_W to NE-SW direction might have existed prior to the Deccan traps volcanism, along which several intrusives.
10
Content available Chemical composition of date-pits and its potential for developing value-added product - a review
71%
Hossain M. Z. , Waly M. I. , Singh V. , Sequeira V. , Rahman M. S.
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tom 64
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nr 4
11
Content available Soil microbial and nutrient dynamics influenced by irrigation-induced salinity and sewage sludge incorporation in sandy - loam textured soil
61%
Ankush , Prakash R. , Kumar R. , Singh V. , Harender , Singh V. K.
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nr 4
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