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Minor rearrangements to CoR, fix bug in granular single

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jtclemm
2024-05-06 16:39:29 -06:00
parent 0344b6af70
commit 3d4bb44911
9 changed files with 120 additions and 64 deletions
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21
doc/src/pair_granular.rst
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@ -187,8 +187,7 @@ for the damping model currently supported are:
2. *mass_velocity*
3. *viscoelastic*
4. *tsuji*
5. *hooke/en*
6. *hertz/en*
5. *coeff_restitution*
If the *damping* keyword is not specified, the *viscoelastic* model is
used by default.
@ -250,20 +249,28 @@ The dimensionless coefficient of restitution :math:`e` specified as part
of the normal contact model parameters should be between 0 and 1, but
no error check is performed on this.
*hooke/en* and *hertz/en* models are useful for cases where a specific normal coefficient of restitution :math:`e` is required. In these models, the normal coefficient of restitution :math:`e` is specified as an input. Following the approach of :ref:`(Brilliantov et al) <Brill1996>`, *hooke/en* calculates the damping coefficient for the *hooke* model as:
The *coeff_restitution* model is useful when a specific normal coefficient of
restitution :math:`e` is required. In these models, the normal coefficient of
restitution :math:`e` is specified as an input. Following the approach of
:ref:`(Brilliantov et al) <Brill1996>`, when using the *hooke* normal model,
*coeff_restitution* calculates the damping coefficient as:
.. math::
\eta_n = \sqrt{\frac{4m_{eff}k_n}{1+\left( \frac{\pi}{\log(e)}\right)^2}},
\eta_n = \sqrt{\frac{4m_{eff}k_n}{1+\left( \frac{\pi}{\log(e)}\right)^2}} ,
*hertz/en* calculates the damping coefficient for the *hertz* and *hertz/material* models using:
For any other normal model, e.g. the *hertz* and *hertz/material* models, the damping
coefficient is:
.. math::
\eta_n = -2\sqrt{\frac{5}{6}}\frac{\log(e)}{\sqrt{\pi^2+(\log(e))^2}}(R_{eff} \delta_{ij})^{\frac{1}{4}}\sqrt{\frac{3}{2}k_n m_{eff}} ,
where :math:`k_n = \frac{4}{3} E_{eff}` for the *hertz/material* model. Since these models calculate the damping coefficients by accounting for the effective mass, effective radius and pairwise overlaps (for *hertz/en*), they accurately reproduce the specified coefficient of restitution for both monodisperse and polydisperse particle pairs.
where :math:`k_n = \frac{4}{3} E_{eff}` for the *hertz/material* model. Since
*coeff_restitution* accounts for the effective mass, effective radius, and
pairwise overlaps (except when used with the *hooke* normal model) when calculating
the damping coefficient, it accurately reproduces the specified coefficient of
restitution for both monodisperse and polydisperse particle pairs.
The total normal force is computed as the sum of the elastic and
damping components: