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Merge pull request #1631 from jibril-b-coulibaly/patch-2

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Bug fixes for pair style granular
This commit is contained in:
Axel Kohlmeyer
2019-10-09 14:14:48 +02:00
committed by GitHub
parent 0cf60d0c62 747bfa31f2
commit 6e244bc8dc
2 changed files with 42 additions and 54 deletions
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22
doc/src/pair_granular.txt
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@ -100,7 +100,7 @@ on particle {i} due to contact with particle {j} is given by:
\mathbf\{F\}_\{ne, Hooke\} = k_N \delta_\{ij\} \mathbf\{n\}
\end\{equation\}
Where \(\delta = R_i + R_j - \|\mathbf\{r\}_\{ij\}\|\) is the particle
Where \(\delta_\{ij\} = R_i + R_j - \|\mathbf\{r\}_\{ij\}\|\) is the particle
overlap, \(R_i, R_j\) are the particle radii, \(\mathbf\{r\}_\{ij\} =
\mathbf\{r\}_i - \mathbf\{r\}_j\) is the vector separating the two
particle centers (note the i-j ordering so that \(F_\{ne\}\) is
@ -177,7 +177,7 @@ following general form:
\end\{equation\}
Here, \(\mathbf\{v\}_\{n,rel\} = (\mathbf\{v\}_j - \mathbf\{v\}_i)
\cdot \mathbf\{n\}\) is the component of relative velocity along
\cdot \mathbf\{n\} \mathbf\{n\}\) is the component of relative velocity along
\(\mathbf\{n\}\).
The optional {damping} keyword to the {pair_coeff} command followed by
@ -299,8 +299,8 @@ the normal damping \(\eta_n\) (see above):
\eta_t = -x_\{\gamma,t\} \eta_n
\end\{equation\}
The normal damping prefactor \(\eta_n\) is determined by the choice of
the {damping} keyword, as discussed above. Thus, the {damping}
The normal damping prefactor \(\eta_n\) is determined by the choice
of the {damping} keyword, as discussed above. Thus, the {damping}
keyword also affects the tangential damping. The parameter
\(x_\{\gamma,t\}\) is a scaling coefficient. Several works in the
literature use \(x_\{\gamma,t\} = 1\) ("Marshall"_#Marshall2009,
@ -308,10 +308,10 @@ literature use \(x_\{\gamma,t\} = 1\) ("Marshall"_#Marshall2009,
tangential velocity at the point of contact is given by
\(\mathbf\{v\}_\{t, rel\} = \mathbf\{v\}_\{t\} - (R_i\Omega_i +
R_j\Omega_j) \times \mathbf\{n\}\), where \(\mathbf\{v\}_\{t\} =
\mathbf\{v\}_r - \mathbf\{v\}_r\cdot\mathbf\{n\}\), \(\mathbf\{v\}_r =
\mathbf\{v\}_j - \mathbf\{v\}_i\). The direction of the applied force
is \(\mathbf\{t\} =
\mathbf\{v_\{t,rel\}\}/\|\mathbf\{v_\{t,rel\}\}\|\).
\mathbf\{v\}_r - \mathbf\{v\}_r\cdot\mathbf\{n\}\{n\}\),
\(\mathbf\{v\}_r = \mathbf\{v\}_j - \mathbf\{v\}_i\).
The direction of the applied force is \(\mathbf\{t\} =
\mathbf\{v_\{t,rel\}\}/\|\mathbf\{v_\{t,rel\}\}\|\) .
The normal force value \(F_\{n0\}\) used to compute the critical force
depends on the form of the contact model. For non-cohesive models
@ -411,8 +411,8 @@ option by an additional factor of {a}, the radius of the contact region. The tan
\mathbf\{F\}_t = -min(\mu_t F_\{n0\}, \|-k_t a \mathbf\{\xi\} + \mathbf\{F\}_\mathrm\{t,damp\}\|) \mathbf\{t\}
\end\{equation\}
Here, {a} is the radius of the contact region, given by \(a = \delta
R\) for all normal contact models, except for {jkr}, where it is given
Here, {a} is the radius of the contact region, given by \(a =\sqrt\{R\delta\}\)
for all normal contact models, except for {jkr}, where it is given
implicitly by \(\delta = a^2/R - 2\sqrt\{\pi \gamma a/E\}\), see
discussion above. To match the Mindlin solution, one should set \(k_t
= 8G\), where \(G\) is the shear modulus, related to Young's modulus
@ -680,7 +680,7 @@ The single() function of these pair styles returns 0.0 for the energy
of a pairwise interaction, since energy is not conserved in these
dissipative potentials. It also returns only the normal component of
the pairwise interaction force. However, the single() function also
calculates 10 extra pairwise quantities. The first 3 are the
calculates 12 extra pairwise quantities. The first 3 are the
components of the tangential force between particles I and J, acting
on particle I. The 4th is the magnitude of this tangential force.
The next 3 (5-7) are the components of the rolling torque acting on