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step function mass flux

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Hello,

I am studying the evaporation of a sessile droplet. I need to use a step function to increase the mass transfer coefficient from 0 to a specific value and I am not sure how I can do it. Should I add a ramp for the time as well?

Can anyone help me with this?

Best wishes,

Mercedes

1 Reply Last Post 18.03.2016, 13:47 GMT-4

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Posted: 8 years ago 18.03.2016, 13:47 GMT-4
Hi
You may add a ramp function by going to:
Definitions-->Functions-->Ramp
Then go to the mass flux setting and type:

flux1+(flux2-flux1)*rm1(t)

For instance, if you want your flux to start from 1e-6 and ends to 1e-3:
1e-6+(1e-3-1e-6)*rm1(t)
Or mass flux from zero to 1e-3:
0+(1e-3-0)*rm1(t)

In the ramp function setting, you can change the time where the function starts. For example, if you want the droplet to start evaporating at t=2, you should set the "location" to 2.

Hope this helps.
Hi You may add a ramp function by going to: Definitions-->Functions-->Ramp Then go to the mass flux setting and type: flux1+(flux2-flux1)*rm1(t) For instance, if you want your flux to start from 1e-6 and ends to 1e-3: 1e-6+(1e-3-1e-6)*rm1(t) Or mass flux from zero to 1e-3: 0+(1e-3-0)*rm1(t) In the ramp function setting, you can change the time where the function starts. For example, if you want the droplet to start evaporating at t=2, you should set the "location" to 2. Hope this helps.

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