## Fluids

Topics relate to Fluent, CFX, Turbogrid and more

#### Setting velocity inlet

• natheodore182
Subscriber

Hello,

I need some help with regards to the setting of my velocity inlet for the simulation of air flow into a nose of the human. We set a simple hemisphere that mimics the entrance of the nose and the mouth where the enclosed box will the velocity inlet.

However, upon setting the velocity of the inlet to be of a specific speed(3.5m/s) and choosing our outlets, the flow actually gets faster when it enters the "nose and mouth" in which we understand because of conservation of mass for the flow, the velocity of the airflow will increase upon entering the "nose and mouth" . But in actual fact what we want is that specific hole to be our inlet speed of 3.5m/s in which the enclosed box being the ambient environment to be 0m/s. We tried setting the "nose and mouth" to be the velocity inlet and setting a negative velocity but as a result no streamline is formed, mainly due to error, which we arent sure either. Is there anyway to get around this? Would appreciate a prompt reply!

• raul.raghav
Subscriber

I'm a little confused with the figure and the what you're trying to simulate here. Could you answer the following questions and comment on the figure attached below?

1. So you interested in modeling airflow into the nose of a human. And you model the nose and mouth entrance together as a hole. You want the velocity at the nose and mouth entrance to be 3.5m/s?

2. Why is there a hole at the end of the hemisphere in the figure? (See below)

3. Does the box just represent the ambient environment? If yes, you don't have to model it. You can set the nose and mouth inlet velocity as 3.5m/s and the the other hole as 0 Pa static pressure condition. Can you explain a little more as to what you're trying to capture exactly?

• natheodore182
Subscriber

The picture above represents if an individual were to wear a mask (simplified drawing because we just got to learn ANSYS)

1) Yes we want the velocity at the entrance to be 3.5m/s

2) The hole at the end of the hemisphere is the entrance of the mouth? while the one you labelled the nose and mouth inlet will be the entrace of the hole in the mask.

3)Yes the box represents the ambient environment. I understand what u mean but we want to capture the flow coming from the ambient environment into the individual's nose and mouth, thats what we want to capture

Nathaniel

• Raef.Kobeissi
Subscriber

You need to create a plane at the outlet of the Hemisphere and collect data from that plane using CFD-POST or Using the Report facility in Fluent. The holes in your schematics appear to be walls instead of actual passage-way for your flow so I don't expect any flow to go through that hole. You have to make sure that the passageway is a fluid domain.

Regards

• raul.raghav
Subscriber

Nathaniel, I "kinda-sorta" understand what you mentioned above. I wanted to suggest you a few things but would you able to upload the workbench archive file so I could take a quick look into the setup.