Hello,
I’m sorry for not being more specific. I was trying to incorporate https://www.mail-archive.com/fipy@nist.gov/msg02626.html by reference. Sketch of problem: (1)------------ Region 1 --------------* thermal contact resistance * ---------- Region 2 ------------ (2) Temperature at (1) is zero. Heat flux at (2) is constant. At time zero, temperature is everywhere zero. ****** What is a thermal contact resistance? https://en.wikipedia.org/wiki/Thermal_contact_conductance A dissertation available free online: Thermal contact resistance Author: Mikic, B. B.; Rohsenow, Warren M. Citable URI: http://hdl.handle.net/1721.1/61449 It’s equation (1.1) on page 12 of this dissertation. Thermal contact resistance is directly analogous to an electrical resistor in a simple circuit: (temperature drop across thermal contact resistance) = (heat flux) * (its unit-area thermal resistance) Units: Kelvin = W/m^2 times Kelvin/(W/m^2) Mathematically, the thermal contact resistance has no thickness and no heat capacity (it does not store energy). ****** Please look at https://www.mail-archive.com/fipy@nist.gov/msg02641.html. Dr. Guyer and Dr. Wheeler considered the case of steady heat flow (steady state problem with no transient term), and their thermal contact has a finite thickness ‘dx’. They derived an expression for effective thermal conductivity at the thermal contact location, and provided FiPy code. How do things change in a transient problem? What is the effective thermal diffusivity (thermal diffusivity = thermal conductivity/(mass density * specific heat)) at the interface location, given that Region 1 and Region 2 have different thermal conductivities, mass densities, and specific heats? How is it written in FiPy? This is the point at which my knowledge of the finite volume method and FiPy is too weak. A solution where the thermal contact has a finite thickness ‘dx’ is also of interest, since it seems like a thermal contact resistance can be approximated by setting ‘dx’ very small. Trying to get on the same page: thermal diffusivity m^2/s thermal conductivity W/m/K mass density kg/m^3 specific heat J/kg/K Thanks On Thu, Jul 12, 2018 at 9:49 AM Daniel Wheeler <daniel.wheel...@gmail.com> wrote: > On Wed, Jul 11, 2018 at 7:00 PM, Drew Davidson <davidson...@gmail.com> > wrote: > > > > 1. Transient heat conduction rather than steady state. Same boundary > > conditions but initial condition can be zero temperature eveywhere. > > Add a TransientTerm to the equation and step through the solution with > time steps and sweeps if necessary. > > > 2. The two regions have differing properties (thermal conductivity, mass > > density, specific heat) > > The coefficients can have spatially varying values in FiPy. Define the > coefficients as face or cell variables. > > > 3. The thermal contact is a true thermal contact resistance (a pure > > resistance); it has zero thickness, and it has zero heat capacity. > > I need to see it defined mathematically to understand how to implement > it in FiPy, but I'm confident it's possible to define it. > > -- > Daniel Wheeler > _______________________________________________ > fipy mailing list > fipy@nist.gov > http://www.ctcms.nist.gov/fipy > [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] >
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