  We elucidate the universal scaling and multiscaling properties of the
nonequilibrium steady states (NESS) in a driven symmetric binary fluid (SBF)
mixture in its homogeneous miscible phase in three dimensions (3d). We show,
for the first time, via Direct Numerical Simulations (DNS) that structure
functions of the velocity and the concentration gradient exhibit multiscaling
in 3d and extended self-similarity (ESS). We also find that, in contrast to the
well-known passive scalar turbulence problem, structure functions of the
concentration show simple scaling. We propose a new shell model for SBF
turbulence which preserve all the invariances in the ideal limit of the SBF
equations and which reduces to a well-known shell model for fluid turbulence in
the zero concentration field limit. We show that the shell model has the same
scaling properties as the 3d SBF equations. Our combined results from our DNS
of the SBF equations and shell-model studies consistently bring out the
multiscaling of the velocity and concentration gradient fields and simple
scaling of the concentration field.
