Simple Fluid Flow!
 

Consider a simple geometry, a rectangular electrolyte bath having an Anode and Cathode as solid surface hanging from top, inlet at the centre bottom position and outlet on the opposite surface at the top left side corner.

I want to simulate only flow of electrolyte no chemistry involved. Fluent 18.2

Case 1: Turbulent K-E model, added a fluid having a constant density and viscosity. Inlet mass flow rate (low value .056 kg/sec) outlet gauge pressure 0.
mass and Momentum completely converged(10^-4 residual)

Case 2: Turbulent K-E model, Energy On and enabled species transport as want to create a mixture. In mixture H2O + H2SO4 + CuSO4 are present and Inlet BC same mass flow rate as previous,temp 65C & mass fraction are specified 70%, 10%, 20% respectively. for Outlet gauge pressure Zero, Temp 65 and same mass fraction as inlet for back flow condition.
Density as Volume wt mixing law
Viscosity as Mass wt mixing law
Mass and Momentum converged(10^-6 & 10^-5) but K and E residual constant fluctuating
1.3-3.3 *10^-4 range

Why I'm getting completely different flow result??

I've attached the stream line, why the hell flow is getting divided at the top zone(image_weird)??

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