Industrial Mixing: The Fundamental Principles You Need to Know

Mixing is often a discreet step, but it’s absolutely vital in many industrial processes. Whether you're blending liquids, dissolving solids, dispersing gas, or keeping particles in suspension, mixing plays a central role in ensuring product quality and process efficiency.

At Milton Roy Mixing, our expertise is built on a deep understanding of these phenomena, combining scientific knowledge with real-world experience. Here’s a clear overview of the key principles behind an effective, long-lasting mixing solution.

Understanding Flow Regimes: Laminar vs. Turbulent

It all starts with a key concept: the Reynolds number, which helps determine how the fluid moves inside the tank.

Laminar regime (Re < 10^4): the fluid flows in smooth, parallel layers with minimal mixing between them. This occurs with very viscous fluids like adhesives or polymers and requires low-shear impellers designed to avoid damaging the product.
Turbulent regime (Re > 10^4): the flow is chaotic and filled with eddies, resulting in much faster and more thorough mixing. This is the most common regime in industry, particularly for low viscosity liquids or chemical reactions.

Key takeaway:

Understanding the flow regime is crucial for choosing the right impeller geometry and rotation speed, ensuring optimal energy transfer without waste.

The Crucial Role of Tank Geometry

An efficient mixer isn’t just about the impeller. The tank itself has a major influence on how the fluid behaves.

Baffles (vertical plates attached to the inside walls) are essential in turbulent flow. They break the central vortex and promote axial flow ensuring better fluid circulation.
Tank bottom shape (dished, conical, flat…) affects solid suspension and ease of emptying the tank.
H/D ratio (liquid height / tank diameter): a ratio close to 1 is often ideal for most industrial mixing applications, promoting good homogenization with minimal dead zones.

Our added value:

We use CFD simulations (Computational Fluid Dynamics) to model fluid behavior in your tank, helping us design highly tailored and accurate mixing systems from the start.

Choosing the Right Mixing Impeller

Every process has its specific goals. The choice of impeller type depends on what you want to achieve:

Flat-blade turbines: generate strong shear, ideal for dispersing gases or solids into liquids.
Axial-flow turbines (HPM or Sabre impellers): create a vertical flow for fast, even mixing.
Rushton turbines: often used for gas dispersion in bioprocessing and reaction.

At Milton Roy Mixing, we don’t believe in one-size-fits-all.
Every impeller is carefully selected, sized, and tested based on your goals, whether that’s maximizing yield, minimizing shear, or enhancing mass transfer.

Milton Roy Mixing CFD simulation for large storage tank with two side-entry mixers on the right

Rotation Speed & Power Draw: Finding the Right Balance

An efficient mixer isn’t just about speed, it’s about delivering the right mixing performance with controlled energy consumption.

Here’s what you need to know:

Too high a speed = risk of excessive shear, wasted energy, abrasion and product degradation (e.g. foaming).
Too low a speed = poor mixing, dead zones, and sediment buildup.

Power draw (P) depends on several factors, expressed in this formula:

P = Np x ρ x N3 x D5

Np = power number,

ρ = fluid density,

N = rotational speed,

D = impeller diameter.

As you can see, impeller diameter (D) has an exponential effect, small changes can significantly impact power requirements.

In Summary

Industrial mixing is based on a complex balance of physics, engineering, and field expertise. A reliable solution requires taking into account all key variables: fluid properties, tank geometry, mixing objectives, impeller type, and power consumption.

At Milton Roy Mixing, we don’t just provide a mixer, we deliver a fully integrated solution, carefully designed, tested, and validated to meet your performance goals.