  The emission of hard X-rays associated with white dwarfs (WD) can be
generated by the presence of a stellar companion either by the companion's
coronal emission or by an accretion disk formed by material stripped from the
companion. Recent studies have suggested that a Jupiter-like planet can also be
donor of material whose accretion onto the WD can generate hard X-rays. We use
the {\sc guacho} code to reproduce the conditions of this WD-planet scenario.
With the example of the hard X-ray WD KPD\,0005+5106, we explore different
terminal wind velocities and mass-loss rates of a donor planet for a future
network of simulations to investigate the luminosity and the spectral and
temporal properties of the hard X-ray emission in WD-planet systems. Our
simulations show that the material stripped from the planet forms a disk and
accretes onto the WD to reach temperatures high enough to generate hard X-rays
as usually seen in X-ray binaries with low-mass companions. For high terminal
wind velocities, the planet material does not form a disk, but it rather
accretes directly onto the WD surface. The simulations reproduce the X-ray
luminosity of another X-ray accreting WD (G\,29$-$38), and only for some times
reaches the hard X-ray luminosity of KPD\,0005+5106. The X-ray variability is
stochastic and does not reproduce the period of KPD\,0005+5106, suggesting that
additional physical processes (e.g., hot spots resulting from magnetic
channelling of the accreting material) need to be explored.
