In the present work, the computer simulations are based on the solution
of the balance equations for the fluid in a domain discretized into
finite-volumes. The flow field is turbulent and three dimensional.
In order to evaluate the effects of the turbulence field,
the Reynolds averaging procedure is applied to Navier-Stokes equations and
Reynolds Averaged Navier-stokes equations (RANS) are obtained.
Turbulence influence on transfer mechanisms is included with a
model. Given the blade passage frequency, the time average of the
velocity field is not zero. Equations are solved with a
transient approach to reproduce effect of blade passage frequency.
Distinctive characteristics of the numerical simulations are (i) a complex geometry, driven by the shape of the impeller; (ii) the presence of a free surface; (iii) the turbulent flow field; (iv) the transient approach required to simulate effects induced by rotation of the impeller.
In this work, the computational domain is accurately tailored to each different configuration examined: (a) the laboratory vessel, (b) the industrial size reactor equipped with the retreated curved blade impeller (CE12500) and (c) the industrial size reactor equipped with the turbofoil turbine (BE12500). In this section, general methods used for all the simulations are discussed.