Color Spraying with Wall Film CFD Simulation

Color Spraying with Wall Film, CFD Simulation by Ansys Fluent Training

In this project, the spraying color on the wall has been simulated with Ansys Fluent software. We used one-way DPM to simulate the discrete phase. The cone injection and particle velocity are equal to the first simulation 10 with a particle diameter of 0.001 m and a spray angle of 45 °. This project aims to determine whether velocity and particle diameter affect the staining. The velocity is 20 meters per second for the second simulation, and the particle diameter is 0.1m. Also, the cone angle is 45 degrees. The DPM Boundary condition Type is wall film so that the color particles stick to the wall. The present simulation process is performed unsteady and in a time step equal to 0.0025 s.

 Geometry & Mesh

The 3D geometry of this project has been produced with SpaceClaim software. The length and width of the computational area are 3 m, and its height is 4 m.

Mesh is created with Ansys Meshing software, and the mesh type is unstructured. The number of cells is 254934.

Color Spraying CFD Simulation

To simulate the color spraying on the wall with wall film, we consider several assumptions:

• The solver is pressure-based.
• The current simulation is unsteady in terms of time.
• We ignored the gravity effect.

Here is a summary of the steps for defining the problem and its solution in the following table:

Models
Viscous model		laminar
Discrete phase		on
	particle treatment	unsteady particle tracking
	material in injection	Color Spray
	particle type in injection	inert
	injection type	cone
	Number of streams	400
Point properties
	Cone-Type	Point-cone
	Start time	0s
	Stop time	0.2s
	Diameter	RUN1:0.001m RUN2:0.1m RUN3:0.1m
	Velocity magnitude	RUN1:10m/s RUN2:20m/s RUN3:20m/s
	Cone angle	RUN1:45deg RUN2:45deg RUN3:30deg
	Total flow rate	1-e20
Boundary conditions
Wall & wall back		wall
	wall motion	stationary wall
	discrete phase BC type	scape
top wall		Wall
	wall motion	stationary wall
	discrete phase BC type	Wall film
Solution Methods
Pressure-velocity coupling		simple
Spatial discretization	pressure	second-order
	momentum	second-order upwind
	Modified turbulent viscosity	first-order upwind
	Initialization
Initialization method		standard

 Color Spraying Results

In this simulation, the spray paint on the wall is simulated using an injector to insert the particles conically. According to the conical angle, the range of motion of the particles is determined.

As mentioned earlier, this project aims to determine whether increasing the velocity and diameter of color particles affects staining. At first, a simulation with a smaller diameter and velocity was performed, which had a good result. Then, in the next simulation, the velocity and diameter of the colored particles increased, so it was observed that the particles spread on the wall. In the next simulation, we reduced the spray angle so that the spraying might be done correctly, which did not happen, and the best way to paint was the first simulation.