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Home Forums ANSYS Fluent Beginners to Advanced level Some doubts in lesson 22 [Expression].

  • Some doubts in lesson 22 [Expression].

    Posted by Pratham on October 23, 2023 at 5:39 pm

    Good evening,

    Hope you are doing well. As from the assignment I have few doubts in building the expression for our temperature. We somehow build the relation between Cp and temperature. And validate the relation from the values from the mentioned site which is quite similar. Relation is as follow

    Cp = a+bT+cT^2+dT^3.

    Where

    Cp is in [KJ/kmol.k]

    T is in [K]

    a=6.938

    b=55.22*e-2

    c=-28.65*e-5

    d=57.69e-9

    The maximum error obtained is 0.72%.

    The average error obtained is 0.20%.

    Above relation is applicable for temperature range 273-1500 K

    Now my question is how we can apply as expression for the problem as for the Cp for hexane is constant and polyline wise in fluent. You will not able to provide the expression there or there is no option for expression .

    If we want to provide expression. Should we give expression to the fluid temperature in order to attain a graph or relation which will not be possible due to invalid units.

    Should we create a data for our personal heat capacity with dependant to temperature for hexane by utilsing UDF to interpret above relation.Hoping to hear from you soon.Hope you will understand.

    Thank you,

    With regards,

    Pratham Chauhan.

    Sandeep replied 5 months, 3 weeks ago 2 Members · 1 Reply
  • 1 Reply
  • Sandeep

    Administrator
    October 23, 2023 at 7:49 pm

    It is simple and straightforward. In fluent by default you will see Cp is constant. To see Cp and other thermal-related properties of hexane, first you need to switch on the energy equation. That will help you to create the expression, Cp =f(T). You have already done the first step, which is to make the correlation, now just convert to expression and apply. Others have already done it.

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