MR-CFD experts are ready for DPM analysis, consulting, training, and CFD simulation.

## DPM

A discrete phase model (DPM) is used when the aim is to investigate the behavior of the particles from a Lagrangian view and a discrete perspective. In fact, the difference between the Lagrangian and the Eulerian view is that fluid behavior in Lagrangian view is examined on the basis of a particle tracking of a particle of fluid flow; Whereas fluid behavior is considered in Eulerian view based on the assumption of a finite volume element in the fluid flow path.

If the behavior of discrete particles in the presence of a continuous flow field is affected by continuous flow, the interaction with the continuous phase must be activated. Also, if the particle tracking is relatively unsteady over time, the unsteady particle tracking option must be activated. The discrete phase can be applied in various physical forms, the type of which depends on the problem model. One of the physical defining modes is the two-way turbulent coupling mode, which is used to study the effects of changes in the turbulent quantities caused by particle damping and Eddy turbulence.

### Injection

Also, the injection process for the mixed flow is defined in the input section of the model. In this way, in the input section of the model, the desired material enters the interior space of the model with the same discrete state or particle by particle. This particle injection as a discrete state can occur in different states. For example, the combusting mode is used when the material is injected into the model’s interior to perform the combustion process.

**Particle flow**

Particle flow is a kind of two-phase flow in which one phase is present continuously, usually named carrier phase. And the other phase (particle phase) consists of small immiscible particles in the fluid flow.

There are three approaches for modeling of particle-primary fluid interaction

- One way –this model just calculates the effect of primary fluid flow on particle path
- Two way –particle fluid flow and carrier fluid flow interact with each other simultaneously
- Four-way. Is like two way but also there is particle-particle interaction

We are expertise in the field of discrete phase model, and we’ve done various project in this filed. DPM simulation has a different application like fuel spray, particle combustion, cyclone, scrubber, etc.

We use ANSYS Fluent software package for modeling discrete phase model. You can see some of our project that we use DPM model

- CFD simulation particle separator from gas using cyclone
- Using particle droplet combustion in two and four-stroke internal combustion engine
- Simulation particle settling by the gravity body force
- Wood combustion using the discrete phase model
- Sand particle tracking in the pond riverside
- Particle tracking in spray dryer using the DPM model
- Simulation of using magnetohydrodynamic (MHD) body force for increasing performance of cyclon
- errosion modeling in knee

Particle flow occurs in many engineering problems. For instance, some of its application areas in the industry are as follows. Fluidized beds, carbon capture, electrostatic reciprocator, solid separator cyclones, etc.. When investigating particle flow, we should take into account different phenomena. For example, the particles influence the overall properties of the fluid flow. They can change the heat transfer rate.

Moreover, different forces can affect particles. Forces such as electrical, electromagnetic and the forces between particles themselves. Designers of mechanical systems have an interest in predicting the trajectory of particles in the fluid flow. This is also very prominent when in the fluid flow charged particles and electromagnetic fields are present simultaneously.

ANSYS Fluent is a powerful CFD tool for the simulation of particle flows, and MR CFD Company is ready to organize your projects in this field.

## Discrete Particle Behavior

Discrete particles have three different types of behavior in the presence of a continuous flow field:

Type 1) Discrete particles are not affected by the continuous phase.

Type 2) Discrete particles are affected by continuous flow (interaction with continuous phase).

Type 3) Discrete particles are affected by themselves, in addition to being affected by continuous phase (DEM collision).

## Discrete Phase Boundary Condition

Discrete phases in boundary areas (such as inlet, outlet, and wall) can exhibit three different behaviors: ESCAPE, TRAP, and REFLECT. Usually, Escape condition is assumed in the inlets and outlets. While walls have Trap or Reflect conditions based on the problem description.

## DPM Application for Erosion CFD Simulation

In ANSYS Fluent software, the erosion can be measured and calculated as an independent parameter. Fluent software is able to calculate the erosion rate by activating the Discrete Phase Modeling (DPM). In previous versions of ANSYS Fluent software, we were only able to calculate erosion in dilute flows, but in newer versions with the addition of DEM-Collision, it is possible to model two-phase flows with more concentration discrete phases taking considering collisions.

We will now discuss how to calculate erosion and its models in ANSYS Fluent software. Many popular erosion models, such as Oka, Maclaury, and Finnie, have been implemented in ANSYS Fluent software. Fluent software also has its own model for calculating erosion. Fluent software also allows the application of other erosion models with User-Defined Functions (UDF).

Fluent software generally defines the amount of particle erosion on the wall boundaries as follows:

### Fluent Model

In the above equation, C (d_p) is a function of particle diameter, θ is the angle of collision with wall, and f (θ) is function of angle of collision, V_p is the relative velocity of particle, and A_face is the wall surface where the collision of the particles is placed, and b (v) is particles relative velocity function.

These values are defined as boundary conditions on the wall and are not part of the properties of the particle in the software, so it should always be noted that these defaults are constant and should always be changed if different materials are used. Therefore, appropriate quantities for the materials used should always be entered. The functions c, f, and b can also be polynomial into the software if needed.

Other models have also been modeled like above in order to increase user power in making changes and comparisons.

### Oka Model

One of the common mistakes in the general use of the mentioned models. It is assumed that if the Oka model is used in certain physics the Maclaury model or other models can be used easily, but it is not true. The reason is that each of the above models is obtained for a particular fluid and particle and the coefficients used are determined according to the experimental conditions and therefore the models cannot be used without correction assumptions. Therefore, the user should adjust the coefficients in each of the above according to their needs and their problem. Another solution is to scale the results and then compare the results of the different models.

## MR CFD

MR-CFD experts are ready to fulfill every Computational Fluid Dynamic (CFD) needs. Our service includes both industrial and academic purposes considering a wide range of CFD problems. MR-CFD services in three main categories of Consultation, Training, and Simulation. MR-CFD company has gathered experts from various engineering fields to ensure the quality of CFD services. Your CFD project would be done in the shortest time, with the highest quality and appropriate cost.

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