SUMMARY

Variable-viscosity fluid flows are widely observed in geophysical and industrial contexts. In contrast to constant viscosity flows (CVFs), variable viscosity flows (VVFs) have viscosity gradients in their flow fields leading to phenomenological differences in their evolution. These gradients alone are the cause of several instabilities than can provoke the onset of turbulence. Further, the alignment of these gradients with the shear field provides another means to accelerate a fluid in a VVF. Irrelevant in CVFs these gradients require terms in the Navier Stokes equations and the total energy budget for turbulence neglected in the CVF case.
The present work involves the development of a facility to observe the effects Variable Viscosity Flows have on turbulence, mixing, and chemical yield. Extensive testing with Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF) have resulted in quantitative data portraying the effect the viscosity variation has on the velocity and concentration fields in a coaxial jet mixer. Additionally, initial efforts are in progress to develop an in-line spectrometer to measure the yield of the same flows when using competitive consecutive reactants of 1-napthol and diazotized sulfanilic acid.
The proposed work is to extend the study to a jet in crossflow and observe the effects the viscosity variation has in the new geometry. This study will extend the understanding of viscosity gradients on turbulence, mixing, and chemical yield. The objectives are to:
1) Implement simultaneous PIV and PLIF to obtain velocity and concentration fields in the jet in crossflow geometry
2) Develop and implement an in-line spectrometric technique to measure the products of the 1-napthol and diazotized sulfanilic acid chemistry
3) Perform a parametric study to investigate the variable viscosity effect on turbulence and mixing in a tee mixer
4) Perform a parameteric study to investigate the variable viscosity effect on chemical yield in a tee mixer
5) Perform a parametric study to investigate the effects of differing inlet geometry coupled with the variable viscosity effect on turbulence and mixing in a tee mixer
6) Perform a parametric study to investigate the effects of differing inlet geometry coupled with the variable viscosity effect have on chemical yield in a tee mixer