I forgot to mention that the [image: P_f] and [image: P_k] values in eqpd
and eqpu are actually as follow,
eqpd:
[image: -\frac{\partial P_d}{\partial t} = C_3 (P_f (0,t) - P_d(t)) + C_4
(P_k(0,t)-P_d(t))]
and eqpu:
[image: \frac{\partial P_u}{\partial t} = C_3 (P_f (L,t) - P_u(t)) + C_4
(P_k(L,t)-P_u(t))]
On Mon, May 9, 2016 at 11:19 AM, Mohammad Kazemi <[email protected]> wrote:
> Thanks for your response. Here are my equations:
>
> eqpk:
>
> [image: \frac{\partial P_k}{\partial t} = D \frac{\partial^2 P_k}{\partial
> x^2}]
> with IC and BCs:
> [image: P_k (x,0) = Pi]
> [image: P_k(0,t) = P_d(t)]
> [image: P_k(L,t) = P_u(t)]
>
> eqpf:
>
> ∂Pf/∂t = C1 ∂2 Pf/∂x2 - C2 (Pf-Pk)
>
> with IC and BCs:
>
> [image: P_f (x,0) = Pi]
> [image: P_f(0,t) = P_d(t)]
> [image: P_f(L,t) = P_u(t)]
>
> eqpd:
>
> [image: - \frac{\partial P_d}{\partial t} = C_3 (P_f - P_k)+C_4 (P_k-P_d)]
>
> with IC:
>
> [image: P_d (0) = Pi]
>
> eqpu:
>
> [image: \frac{\partial P_u}{\partial t} = C_3 (P_f - P_u)+C_4 (P_k-P_u)]
>
> with IC:
>
> [image: P_u (0) = Pi]
>
> So [image: P_k] and [image: P_f] are functions of space and time while [image:
> P_d] and [image: P_u] are only function of time. How should i define a
> variable which is only a function of time? If I want to have schematic of
> problem, it is as below.
>
>
>
>
>
> The pressure in tanks [image: P_u] and [image: P_d] are uniform and only
> changes with time.
>
> I appreciate it,
>
>
>
>
> On Mon, May 9, 2016 at 9:43 AM, Guyer, Jonathan E. Dr. (Fed) <
> [email protected]> wrote:
>
>> By declaring Pd and Pu as CellVariables, you are declaring them to be
>> functions of space. That's what a CellVariable is.
>>
>> Furthermore, eqpd and eqpu depend on Pf and Pk, so that necessitates that
>> Pd and Pu are functions of space.
>>
>> Can you show us the math for the equations you are trying to solve?
>>
>> > On May 7, 2016, at 1:12 PM, Mohammad Kazemi <[email protected]> wrote:
>> >
>> > Thank you. It is running now, but I have a question. Pf and Pk are
>> functions of location (x) and time (t). However, Pd and Pu are only
>> functions of time (they represent pressure at downstream and upstream
>> tanks). When I solve this problem, I will get a vector for Pd and Pu (at
>> last timestep) which varies with location. For example, for Pu,
>> >
>> > print Pu
>> >
>> > [ 7171802.05029459 7171719.44929532 7171632.68237858 7171538.95796536
>> > 7171435.46595385 7171319.37283423 7171187.81897787 7171037.91833804
>> > 7170866.76056175 7170671.41527712]
>> >
>> > Which shows the Pu values at 10 different mesh blocks. Is it related to
>> how I define my cell variables?
>> >
>> > I appreciate your helps.
>> >
>> > Bests,
>> >
>> > On Fri, May 6, 2016 at 5:21 PM, Daniel Wheeler <
>> [email protected]> wrote:
>> > The following runs for me with a few changes.
>> >
>> > On Fri, May 6, 2016 at 1:25 PM, Mohammad Kazemi <[email protected]>
>> wrote:
>> > >
>> > > Pk.constrain([Pd], mesh.facesLeft)
>> > > Pk.constrain([Pu], mesh.facesRight)
>> >
>> > Pk.constrain(Pd.faceValue, mesh.facesLeft)
>> > Pk.constrain(Pu.faceValue, mesh.facesRight)
>> >
>> > > Pf.constrain([Pd], mesh.facesLeft)
>> > > Pf.constrain([Pu], mesh.facesRight)
>> >
>> > Pf.constrain(Pd.faceValue, mesh.facesLeft)
>> > Pf.constrain(Pu.faceValue, mesh.facesRight)
>> >
>> > This makes sense since the Pf and Pk are scalars and [Pd] and [Pu] are
>> > effectively vectors. Also the face value is required since the
>> > constraint is on the faces.
>> >
>> > I hope this helps.
>> >
>> > --
>> > Daniel Wheeler
>> > _______________________________________________
>> > fipy mailing list
>> > [email protected]
>> > http://www.ctcms.nist.gov/fipy
>> > [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
>> >
>> >
>> >
>> > --
>> > Mohammad Kazemi
>> > West Virginia University
>> > Department of Petroleum and Natural Gas Engineering
>> > _______________________________________________
>> > fipy mailing list
>> > [email protected]
>> > http://www.ctcms.nist.gov/fipy
>> > [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
>>
>>
>> _______________________________________________
>> fipy mailing list
>> [email protected]
>> http://www.ctcms.nist.gov/fipy
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>>
>
>
>
> --
> Mohammad Kazemi
> West Virginia University
> Department of Petroleum and Natural Gas Engineering
>
--
Mohammad Kazemi
West Virginia University
Department of Petroleum and Natural Gas Engineering
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