The HertzMindlin with JKR Model
This contact model works within the contact zone and allows you to model strongly adhesive systems, such as dry powders or wet materials. In this model, the implementation of normal elastic contact force is based on the JohnsonKendallRoberts theory (Johnson, Kendal and Roberts 1971).
HertzMindlin with JKR Cohesion uses the same calculations as the HertzMindlin (no slip) contact model for the following types of forces:
 Tangential elastic force
 Normal dissipation force
 Tangential dissipation force
JKR normal force depends on the overlap δ and the interaction parameter, surface energy γ as follows:
Here, E* is equivalent Young’s modulus, and R* is the equivalent radius defined in the “HertzMindlin (no slip) Contact Model” section.
Normal force is a function of normal overlap. HertzMindlin with JKR cohesion model results are compared with the HertzMindlin (no slip) model results. Negative overlap is the gap between two separated particles.
The EDEM JKR normal force follows the same solution of the above equations for both loading and unloading phases. The figure shows the typical plot of JKR normal force as a function of normal overlap.
For γ = 0, force turns into HertzMindlin normal force:
This model provides attractive cohesion forces even if the particles are not in physical contact. The maximum gap between particles with nonzero force is defined as:
For δ< δ_{c} , the model returns zero force. The maximum value of the cohesion force occurs when particles are not in physical contact and the separation gap is less than δ_{c}. The value of maximum cohesion force, called pullout force, is defined as:
Friction force calculation is different than in the HertzMindlin (no slip) contact model in that it depends on the positive repulsive part of JKR normal force. As a result, the EDEM JKR friction model provides higher friction force when cohesion component of the contact force is higher. The importance and advantages of this friction force model correction in the presence of strong cohesive forces was noted and illustrated in, such as (Baran, et al. 2009), (Gilabert, Roux and Castellanos 2007).
Although this model was designed for fine, dry particles, it can be used to model wet particles. The force needed to separate two particles depends on the liquid surface tension γ_{c} and the wetting angle θ:
Equating the above force to JKR max force allows JKR surface energy parameter estimation if EDEM particle size is not scaled.
Interaction  Configurable Parameters  Position 
Particle to Particle, Particle to Geometry 
Click + to add cohesion to particleparticle or particlegeometry interactions. Set the surface energy for each interaction. Surface energy is a property of the materials ability to retain moisture/charge on its surface. The amount of surface energy influences the adhesion of the material. The SI units of surface energy are J/m².  Last 

Select the required category from the Interaction pulldown in the Physics section of the Creator.

Click the + dropdown and then select HertzMindlin with JKR Cohesion.

Click the configuration icon to define contact model parameters.
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