Modelling a problem in polar coordinates on GPyro

[Auriane Javaloyes]

Hello all,

I am studying the ignition of vegetation by hot metal particles ejected by power lines, I want to model on Gpyro the pyrolysis that may occur when the particle reaches the ground.

I am considering (see picture attached) a spherical metal particle of diameter d, temperature Tp(t) (temperature only depends on time as Bi<<1) that's half embedded in a solid fuel bed of vegetation (typically dry grass). The fuel bed is considered to be a rectangle of fixed dimension. The picture below shows a cross-section view. 

The particle transfers heat to the fuel bed, the heat flux transferred by the particle varies over time as the temperature of the particle also varies as a function of t. This problem is intuitively expressed using polar coordinates ((r, theta), but invariance on the theta axis). However, Gpyro is configured to model problems in x,y,z coordinates.

Would someone have an idea on how to implement this case on Gpyro?

Thank you