[modorous]

Hi,

I'm trying to define the viscosity of a liquid as a temperature dependent polynomial function in Fluent.

I plotted the experiment data in Excel to get the trend line and polynomial equation. Pls, see "Excel poly.jpg" to see the experimental data and polynomial function.

When I tried to enter the coefficients in Fluent to define viscosity, I got a completely wrong graph. Pls, see "Fluent poly.png" to see the Fluent graph I got for the polynomial function.

Can you pls tell me what I have done wrong?

Thanks in advance.
Best regards,
M

[CFDKareem]

Originally Posted by modorous

Hi,

I'm trying to define the viscosity of a liquid as a temperature dependent polynomial function in Fluent.

I plotted the experiment data in Excel to get the trend line and polynomial equation. Pls, see "Excel poly.jpg" to see the experimental data and polynomial function.

When I tried to enter the coefficients in Fluent to define viscosity, I got a completely wrong graph. Pls, see "Fluent poly.png" to see the Fluent graph I got for the polynomial function.

Can you pls tell me what I have done wrong?

Thanks in advance.
Best regards,
M

Try increasing the significant figures in your trendline. Rounding error between .123456 and 5.6e-5 can be significant in a high order polynomial.

[modorous]

Thanks, Your suggestion helped.

Increasing the significance of the coefficients helped.

Thanks again.