[amir2920]

Hi,

In my simulation I want to define an air droplet in water. How can I set the initial air drop (a circle in 2D simulation )?

[me3840]

Create a cylindrical coordinate system at the center of the drop. Then use a field function to specify an R value for the size of the droplet, and use that as the initial condition.

[amir2920]

Thank you so much for your reply. I am new to STARCCM+ and have not worked with field function. How can I define this field function? I read the software help and I could not figure that out. Could you help me with that too? I really appreciate your help.

The other question is that can I put an initial velocity for the droplet?

Thanks,

[me3840]

Read the field function programming reference in the help guide.

Consider a cylindrical coordinate system "cylSys". Pretend the drop is 0.2m in size. r=0 is the center of the drop.

We need a field function that returns a value 1 inside the drop and 0 elsewhere. Call the coordinate system in a conditional, saying if r is below 0.2, then 1, else 0.

$$Centroid(@CoordinateSystem("cylSys"))[0]<0.2?1:0

[amir2920]

Originally Posted by me3840

Read the field function programming reference in the help guide.

Consider a cylindrical coordinate system "cylSys". Pretend the drop is 0.2m in size. r=0 is the center of the drop.

We need a field function that returns a value 1 inside the drop and 0 elsewhere. Call the coordinate system in a conditional, saying if r is below 0.2, then 1, else 0.

$$Centroid(@CoordinateSystem("cylSys"))[0]<0.2?1:0

Thank you so much.
I used this field function to define the droplet in my initial condition. But I have another question. How can I specify an initial velocity for this drop? Thanks,

[me3840]

Do it the same way, just replace Centroid with Velocity