A numerical study of transient natural convection heat and mass transfer along a vertical complex wavy surface has been performed. A complex wavy surface was created from two sinusoidal functions, a fundamental wave and its first harmonic. The complex wavy surface is maintained at uniform wall temperature and constant wall concentration. An implicit finite-difference scheme is used for analysis. The numerical results demonstrate that the additional harmonic substantially alters the flow field, temperature and concentration distribution near the surface. Also the numerical results show that the local heat and mass transfer rate for a complex surface are smaller than of a flat plate. This decreased local heat and mass transfer rate seems to depend on the ratio of amplitude surface. پرونده مقاله

In this work, nanostructured NiTi shape memory alloy with equal atomic percentage was produced through mechanical alloying. The result exhibited that after 60 h of mechanical alloying of high purity elemental powder mixtures of nickel and titanium by a planetary high-energy ball mill, the Ti dissolved into Ni lattice and NiTi (B2) phase with was obtained. The XRD investigations, SEM observations, TEM examinations and microhardness results concluded that this method is a powerful and high productive process for preparing NiTi shape memory alloy with nanocrystalline structure and appropriate morphology. پرونده مقاله