Mixing is performed in this turbulent mixer through a three-bladed impeller and the placement of two rods to disturb flow. The model also considers the shape of the free surface.
As an add-on to the CFD Module, the Mixer Module allows you to analyze fluid mixers and stirred reactors. Aided by dedicated functionality for simulating fluid flow subjected to rotating machinery, the Mixer Module also provides material data for modeling different fluids and free surfaces.
Mixers with rotating parts are used in many industrial processes, such as the production of consumer products, pharmaceuticals, food, and fine chemicals. Often, a mixer may be used in batch processes for many different purposes, even on a day-to-day basis, where products are produced at low volumes and sold at high prices.
One thing all mixing processes have in common is that quality, reproducibility, and uniformity of the products is of utmost importance. One way of making sure that these product requirements are met is to perform simulations in order to design and optimize the operation of the mixing process and the mixer itself. Models and simulations are particularly useful when they can be validated by a pilot process, and then be used for scale-up computations. Once validated, such models may be used to avoid the costs involved in building and running pilot scale processes, and instead go directly from the lab scale to full-scale production.
The purpose of the Mixer application is to provide a user-friendly interface where scientists, process designers, and process engineers can investigate the influence that vessels, impellers, baffles, and operating conditions have on the mixing efficiency and the power that is required to drive the impellers. You can use the app to understand and optimize the design and operation of a mixer for a given fluid.
You can specify the dimensions of the vessel, from a list of three types; and the dimensions and configuration of the impellers, from a list of eleven types. The vessels can also be equipped with baffles. You can further specify the properties of the fluid that is being mixed as well as the impeller speed.
This model provides you with tools to build a variety of mixers by combining two common types of vessels with two types of impellers. The mixers are baffled flat and dished bottom vessels with either pitched blade impellers or Rushton turbines. The model includes three examples using the Rotating Machinery, Fluid Flow branch with the frozen-rotor study type. The first example solves a laminar mixing problem in a flat bottom mixer with a Rushton turbine. The second and third examples solve for turbulent mixing in a dished bottom mixer with a pitched blade impeller using the k-epsilon and k-omega turbulence models.
This tutorial example simulates the flow in a flat bottom mixer containing, agitated by a pitched four blade impeller, where the fluid is water, and flow is assumed to be turbulent. The flow in the mixer is modeled using the k-ε turbulence model, and a time-dependent simulation corresponding to 30 revolutions of the impeller is performed in order to reach the operating conditions of the mixer.
When postprocessing the results, the self-similarity of the axial flow along the baffles is analyzed. In agreement with literature, the normalized velocity profiles at different axial positions are found to be self-similar indicating that the flow in this region resemble a three dimensional wall jet.