[mrteo]

Hi all,

I have recently picked up a project where I need to simulate the spread of covid19 particles in the outdoors. I did up a simple geometry to do a simple simulation. This geometry is created from solidworks. (as shown in attached) The big box as the fluid domain and the smaller figure is a human.

I am not quite sure if I require to use a boolean to subtract the body out of the fluid domain. Should I use a boolean?

For the solver settings:
I was using a transient flow without any gravity. I used a RNG K-epil model with enhanced wall treatment and turned on the DPM model. In the DPM model, should I be using the interaction with continuous phase or not?

For my cell zone conditions, I kept facing this message which states "Warning: Flow boundary zone is adjacent to a solid". I tried to change my human from a solid material to a fluid material. However, this seems like a wrong way.

If I did not use a subtract boolean:
For my boundary conditions, I have set 3 sides of my fluid domain as a symmetry type. (IS that correct?) The bottom surface as a wall type (no slip) and I have a inlet to simulate the wind. For the body, I set it as the wall (no slip) and the mouth --> as a (velocity-inlet). However, the arrows on the mouth is pointing inwards. How do I change that??

Hence, when I am in the CFD post, I can only see the streamline of the particles that goes from the mouth to inside the human body. How do I rectify this problem? I am stuck. Please help!!!

[RF_]

Originally Posted by mrteo

Hi all,

I have recently picked up a project where I need to simulate the spread of covid19 particles in the outdoors. I did up a simple geometry to do a simple simulation. This geometry is created from solidworks. (as shown in attached) The big box as the fluid domain and the smaller figure is a human.

I am not quite sure if I require to use a boolean to subtract the body out of the fluid domain. Should I use a boolean?

For the solver settings:
I was using a transient flow without any gravity. I used a RNG K-epil model with enhanced wall treatment and turned on the DPM model. In the DPM model, should I be using the interaction with continuous phase or not?

For my cell zone conditions, I kept facing this message which states "Warning: Flow boundary zone is adjacent to a solid". I tried to change my human from a solid material to a fluid material. However, this seems like a wrong way.

If I did not use a subtract boolean:
For my boundary conditions, I have set 3 sides of my fluid domain as a symmetry type. (IS that correct?) The bottom surface as a wall type (no slip) and I have a inlet to simulate the wind. For the body, I set it as the wall (no slip) and the mouth --> as a (velocity-inlet). However, the arrows on the mouth is pointing inwards. How do I change that??

Hence, when I am in the CFD post, I can only see the streamline of the particles that goes from the mouth to inside the human body. How do I rectify this problem? I am stuck. Please help!!!

Hi
you must subtract the body from the domain, because you did not need the body, you just need the fluid domain.
about DPM model. it is depend on what Accuracy you want. because of very small size of particles it is not false if you don't active interaction with continuous phase.
based on your geometry, it is not correct to use symmetry for 3 side, because you have an inlet velocity boundary. depend on what place you want to simulate (at a room or out space) you should select your boundaries. for example, if you want to simulate the human in out space, you can use pressure outlet for the other walls (except for the bottom wall).

[mrteo]

Hi RF_! Thanks for replying! I did what you said changing the 3 sides to pressure outlets. However, there are no particles actually coming out of the mouth at all? What seems to be the problem here?

IN my solver's console, there is a statement which states, "Note: zone-surface: cannot create surface from sliding interface zone: creating empty surface". Is that okay?

I also could not see any arrows shown on the mouth when I changed the mouth_contact_surface_region to velocity_inlet. (as shown in the pics attached)

At the end of the run, there was no particles that was being tracked at all. (as shown in the pic attached below too).

What could be the cause? Why am I not able to have any particles coming out?

[mrteo]

Originally Posted by RF_

Hi
you must subtract the body from the domain, because you did not need the body, you just need the fluid domain.
about DPM model. it is depend on what Accuracy you want. because of very small size of particles it is not false if you don't active interaction with continuous phase.
based on your geometry, it is not correct to use symmetry for 3 side, because you have an inlet velocity boundary. depend on what place you want to simulate (at a room or out space) you should select your boundaries. for example, if you want to simulate the human in out space, you can use pressure outlet for the other walls (except for the bottom wall).

Hi RF_! Thanks for replying! I did what you said changing the 3 sides to pressure outlets. However, there are no particles actually coming out of the mouth at all? What seems to be the problem here?

IN my solver's console, there is a statement which states, "Note: zone-surface: cannot create surface from sliding interface zone: creating empty surface". Is that okay?

I also could not see any arrows shown on the mouth when I changed the mouth_contact_surface_region to velocity_inlet. (as shown in the pics attached)

At the end of the run, there was no particles that was being tracked at all. (as shown in the pic attached below too).

What could be the cause? Why am I not able to have any particles coming out?0particles_human1_boolean_po.JPG

creating_empty-surface.jpg

no_inlet_at-solver.JPG

[RF_]

Originally Posted by mrteo

Hi RF_! Thanks for replying! I did what you said changing the 3 sides to pressure outlets. However, there are no particles actually coming out of the mouth at all? What seems to be the problem here?

IN my solver's console, there is a statement which states, "Note: zone-surface: cannot create surface from sliding interface zone: creating empty surface". Is that okay?

I also could not see any arrows shown on the mouth when I changed the mouth_contact_surface_region to velocity_inlet. (as shown in the pics attached)

At the end of the run, there was no particles that was being tracked at all. (as shown in the pic attached below too).

What could be the cause? Why am I not able to have any particles coming out?

did you subtract the human body from domain? I guess, you didn't subtract it. you must have one cell zone in cell zone condition.
This Note is because you have two cell zone conditions. the human body must be deleted from fluid domain.