2,784 research outputs found
Hydrologic homogeneous regions using monthly Streamflow in Turkey
Cluster analysis of gauged streamflow records into homogeneous and robust regions is an important tool for the characterization of hydrologic systems. In this paper we applied the hierarchical cluster analysis to the task of objectively classifying streamflow data into regions encompassing similar streamflow patterns over Turkey. The performance of three standardization techniques was also tested, and standardizing by range was found better than standardizing with zero mean and unit variance. Clustering was carried out using Ward’s minimum variance method which became prominent in managing water resources with squared Euclidean dissimilarity measures on 80 streamflow stations. The stations have natural flow regimes where no intensive river regulation had occurred. A general conclusion drawn is that the zones having similar streamflow pattern were not be overlapped well with the conventional climate zones of Turkey; however, they are coherent with the climate zones of Turkey recently redefined by the cluster analysis to total precipitation data as well as homogenous streamflow zones of Turkey determined by the rotated principal component analysis. The regional streamflow information in this study can significantly improve the accuracy of flow predictions in ungauged watersheds
Numerical study of self-similar natural convection mass transfer from a rotating cone in anisotropic porous media with Stefan blowing and Navier slip
A mathematical model is presented for laminar, steady natural convection mass transfer in boundary layer
flow from a rotating porous vertical cone in anisotropic high permeability porous media. The transformed boundary
value problem is solved subject to prescribed surface and free stream boundary conditions with a MAPLE 17
shooting method. Validation with a Chebyshev spectral collocation method is included. The influence of tangential
Darcy number, swirl Darcy number, Schmidt number, rotational parameter, momentum (velocity slip), mass slip and
wall mass flux (transpiration) on the velocity and concentration distributions is evaluated in detail. The computations
show that tangential and swirl velocities are enhanced generally with increasing permeability functions (i.e. Darcy
parameters). Increasing spin velocity of the cone accelerates the tangential flow whereas it retards the swirl flow. An
elevation in wall suction depresses both tangential and swirl flow. However, increasing injection generates
acceleration in the tangential and swirl flow. With greater momentum (hydrodynamic) slip, both tangential and swirl
flows are accelerated. Concentration values and Sherwood number function values are also enhanced with
momentum slip, although this is only achieved for the case of wall injection. A substantial suppression in tangential
velocity is induced with higher mass (solutal) slip effect for any value of injection parameter. Concentration is also
depressed at the wall (cone surface) with an increase in mass slip parameter, irrespective of whether injection or
suction is present. The model is relevant to spin coating operations in filtration media (in which swirling boundary
layers can be controlled with porous media to deposit thin films on industrial components), flow control of mixing
devices in distillation processes and also chromatographical analysis systems
Finite element analysis of rotating oscillatory magneto-convective radiative micropolar thermo-solutal flow
Micropolar fluids provide an alternative mechanism for simulating micro-scale and molecular fluid mechanics which require less computational effort. In the present paper, a numerical analysis is conducted for the primary and secondary flow characterizing dissipative micropolar convective heat and mass transfer from a rotating vertical plate with oscillatory plate velocity, adjacent to a permeable medium. Owing to high temperature, thermal radiation effects are also studied. The micropolar fluid is also chemically-reacting, both thermal and species (concentration) buoyancy effects and heat source/sink are included. The entire system rotates with uniform angular velocity about an axis normal to the plate. Rosseland’s diffusion approximation is used to describe the radiative heat flux in the energy equation. The partial differential equations governing the flow problem are rendered dimensionless with appropriate transformation variables. A Galerkin finite element method is employed to solve the emerging multi-physical components of fluid dynamics problem are examined for a variety of parameters including rotation parameter, radiation-conduction parameter, micropolar coupling parameter, Eckert number (dissipation), reaction parameter, magnetic body force parameter and Schmidt number. A comparison with previously published article is made to check the validity and accuracy of the present finite element solutions under some limiting case and excellent agreement is attained. The current simulations may be applicable to various chemical engineering systems, oscillating rheometry, and rotating MHD energy generator near-wall flows
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