AN INVESTIGATION ON INTERNAL THERMAL FLOW OF NON-NEWTONIAN FLUID

In the present paper an unsteady thermal flow of non-Newtonian fluid is investigated which is of the flow into axisymmetric mould cavity. In the second part an unsteady thermal flow of upper-convected Maxwell fluid is studied. For the flow into mould cavity the constitutive equation of power-law fluid is used as a Theological model of polymer fluid. The apparent viscosity is considered as a function of shear rate and temperature. A characteristic viscosity is introduced in order to avoid the nonlinearity due to the temperature dependence of the apparent viscosity. As the viscosity of the fluid is relatively high the flow of the thermal fluid can be considered as a flow of fully developed velocity field. However, the temperature field of the fluid flow is considered as an unsteady one. The governing equations are constitutive equation, momentum equation of steady flow and energy conservation equation of non-steady form. The present system of equations has been solved numerically by the splitting difference method. The numerical results show that the splitting difference method is suitable for the 2D problem of non-Newtonian fluid. The present application of the splitting diffference method is at first developed by us for non-Newtonian case. For the unsteady flow in the tube the finite difference scheme is given which leads to a tridiagonal system of equations.

APPLICATION OF FDS SCHEME TO 2D DEPTH-AVERAGED FLOW-POLLUTANTS SIMULATION

A Fulx Difference Splitting (FDS) scheme was used in a 2D depth-averagedflow-pollutant model. Within the framework of the Finite Volume Method (FVM) a 2D simulation wastransferred into solving a series of local ID problems based on the rotational invariance propertyof the flux. The FDS scheme was employed to estimate the normal numerical flux of variablesincluding water mass, momentum and pollutant concentration across the interface between cells. Thescheme was checked with exact solutions and verified by observations in the Nantong reach of theYangtze River. Calculated results well match both exact solutions and observations.

A Third-Order Upwind Compact Scheme on Curvilinear Meshes for the Incompressible Navier-Stokes Equations

This paper presents a new version of the upwind compact finite difference scheme for solving the incompressible Navier-Stokes equations in generalized curvilinear coordinates.The artificial compressibility approach is used,which transforms the elliptic-parabolic equations into the hyperbolic-parabolic ones so that flux difference splitting can be applied.The convective terms are approximated by a third-order upwind compact scheme implemented with flux difference splitting,and the viscous terms are approximated by a fourth-order central compact scheme.The solution algorithm used is the Beam-Warming approximate factorization scheme.Numerical solutions to benchmark problems of the steady plane Couette-Poiseuille flow,the liddriven cavity flow,and the constricting channel flow with varying geometry are presented.The computed results are found in good agreement with established analytical and numerical results.The third-order accuracy of the scheme is verified on uniform rectangular meshes.

Satellite remote sensing of volcanic ash cloud in complicated meteorological conditions

Volcanic ash cloud has serious impacts on aviation.With volcanic ash dispersion,it also has a profound and long-term impact on climate and the environment.A new volcanic ash cloud detecting method (SWIR-TIR Volcanic Ash method,STVA) is presented that uses satellite images of Medium Resolution Spectral Imager (MERSI) and Visible and Infrared Radiometer (VIRR) on board the second generation Polar-Orbiting meteorological satellite of China (FY-3A).STVA is applied in detecting Iceland's Eyjafjallajokull volcano eruption.Compared with the traditional Split Window Temperature Difference method (SWTD),the results show that STVA is more sensitive to volcanic ash cloud than SWTD and can fairly extract volcanic ash information from the background of meteorological cloud and the ocean.Ash Radiance Index (ARI) and Absorbing Aerosol Index (AAI) derived from Metop-A satellite images are used to validate the performance of STVA.It is shown that STVA provides similar results with ARI and AAI.FY-3A/MERSI,VIRR and Terra /MODIS data are used to test STVA and SWTD.It is demonstrated that STVA derived from FY-3A satellite data is more effective in complicated meteorological conditions.This study shows great potential of using China's own new generation satellite data in future global volcanic ash cloud monitoring operation.