Resources
User Interview
Exploring the Potential of Replacing Empirical Rules with Theoretical Foundations
Ajinomoto Co., Inc.
Ensuring the Validity of Models: Building Trust in Computational Results
National Institute of Advanced Industrial Science and Technology (AIST)
Technical Column
What’s Powder?
Matter is classified into three states: “solid,” “liquid,” and “gas.” From the perspective of shape and volume, a simple explanation is as follows: “solid” is a state where both shape and volume do not change, “liquid” is a state where shape can change freely but volume remains constant, and “gas” is a state where both shape and volume can change freely.
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Angle of repose
“Angle of repose” is one of the commonly used physical properties to indicate the flowability of powders. The angle of repose refers to the angle formed between the natural slope of a pile of powder that has settled quietly on a horizontal surface and the horizontal plane.
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Fluidity of Powder
The action of “moving powders” is the most fundamental operation in powder handling. For instance, when discharging powder from a hopper, the powder is moved within the hopper by the force of gravity, allowing it to flow smoothly. While it’s a very basic operation to “move powders,” understanding and effectively managing their movement presents considerable challenges.
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Particle size distribution
Powders consist of particles with varying particle sizes, so in many cases, the particle sizes of individual particles are managed collectively as a distribution. This distribution is referred to as “particle size distribution” or “granulometry distribution.” Particle size distribution is represented using acquired data through “frequency distribution (histogram)” and “cumulative distribution.”
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Density
Particle size, along with density, is also an important characteristic that determines the properties of powders. Density, as you are aware, is defined as the mass per unit volume. However, for powders, density isn’t uniquely defined by the term alone. There are generally two types of density for powders: the primary property called “particle density” and the secondary property known as “bulk density” or “powder density,” which refers to the density of the assembly of particles.Read More
DEM Simulation
In recent years, simulations have become increasingly prevalent in various fields. In this series, we will delve into the simulation of powders to provide detailed insights. Among the methods for simulating powder behavior, the Discrete Element Method (DEM) is one widely used approach worldwide. The concept behind DEM is straightforward: it involves simulating the motion of individual particles to represent the collective behavior of the entire powder assembly. Consequently, calculations are performed for the movement of each individual particle.Read More
Contact Force
When considering the motion of particles, numerous forces need to be taken into account. This means there are many factors to consider as “applied forces” in the equations of motion. These forces include “gravity,” “adhesive forces” between particles, “fluid resistance” when considering fluid interactions, and so on – the list can be extensive. Among these factors, the interaction force between particles, commonly known as “contact force,” is almost always crucial to consider, and it’s a distinctive aspect of DEM calculations.
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Adhesion Force: vander waal force
When considering the behavior of powders, there are forces other than contact forces to take into account. Among them, the adhesion force, which occurs between particles or between particles and walls as they attempt to adhere to each other, is a crucial element when handling powders. The van der Waals force is one of the adhesion forces and is a force that arises between atoms or molecules.
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Adhesion Force: Liquid bridge force
When considering the behavior of powders, there are forces other than contact forces to take into account. Among them, the adhesion force, which occurs between particles or between particles and walls as they attempt to adhere to each other, is a crucial element when handling powders. Capillary force, also known as liquid bridging force, is one of the adhesive forces that come into play when particles are connected by a liquid.
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