tuse unicode symbols for parameters in interaction - Granular.jl - Julia package for granular dynamics simulation
(HTM) git clone git://src.adamsgaard.dk/Granular.jl
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---
(DIR) commit fe6e958bbd175c28451ad9047efff6825c2d38b0
(DIR) parent 7fe5b27334a798544f5a5ae76b8c259026d37e65
(HTM) Author: Anders Damsgaard <andersd@riseup.net>
Date: Wed, 24 May 2017 16:04:56 -0400
use unicode symbols for parameters in interaction
Diffstat:
M src/interaction.jl | 188 +++++++++++++++----------------
1 file changed, 89 insertions(+), 99 deletions(-)
---
(DIR) diff --git a/src/interaction.jl b/src/interaction.jl
t@@ -39,8 +39,8 @@ Resolve an grain-to-grain interaction using a prescibed contact law. This
function adds the compressive force of the interaction to the ice floe
`pressure` field of mean compressive stress on the ice floe sides.
-The function uses the macroscopic contact parameterization based on Young's
-modulus and Poisson's ratio if Young's modulus is a positive value.
+The function uses the macroscopic contact-stiffness parameterization based on
+Young's modulus and Poisson's ratio if Young's modulus is a positive value.
"""
function interactIceFloes!(simulation::Simulation, i::Int, j::Int, ic::Int)
t@@ -54,119 +54,109 @@ function interactIceFloes!(simulation::Simulation, i::Int, j::Int, ic::Int)
r_i = simulation.ice_floes[i].contact_radius
r_j = simulation.ice_floes[j].contact_radius
- # Floe distance
- delta_n = dist - (r_i + r_j)
+ # Floe distance; <0: compression, >0: tension
+ δ_n = dist - (r_i + r_j)
+
+ # Local axes
+ n = p/dist
+ t = [-n[2], n[1]]
+
+ # Contact kinematics
+ vel_lin = simulation.ice_floes[i].lin_vel -
+ simulation.ice_floes[j].lin_vel
+ vel_n = dot(vel_lin, n)
+ vel_t = dot(vel_lin, t) -
+ harmonicMean(r_i, r_j)*(simulation.ice_floes[i].ang_vel +
+ simulation.ice_floes[j].ang_vel)
+
+ # Correct old tangential displacement for contact rotation and add new
+ δ_t0 =simulation.ice_floes[i].contact_parallel_displacement[ic]
+ δ_t = dot(t, δ_t0 - (n*dot(n, δ_t0))) + vel_t*simulation.time_step
+
+ # Effective radius
+ R_ij = harmonicMean(simulation.ice_floes[i].contact_radius,
+ simulation.ice_floes[j].contact_radius) - abs(δ_n)/2.
+
+ # Contact mechanical parameters
+ if simulation.ice_floes[i].youngs_modulus > 0. &&
+ simulation.ice_floes[j].youngs_modulus > 0.
+
+ E = harmonicMean(simulation.ice_floes[i].youngs_modulus,
+ simulation.ice_floes[j].youngs_modulus)
+ ν = harmonicMean(simulation.ice_floes[i].poissons_ratio,
+ simulation.ice_floes[j].poissons_ratio)
+
+ # Contact area
+ A_ij = R_ij*min(simulation.ice_floes[i].thickness,
+ simulation.ice_floes[j].thickness)
+
+ # Effective normal and tangential stiffness
+ k_n = E*A_ij/R_ij
+ #k_t = k_n*ν # Kneib et al 2016
+ k_t = k_n*2.*(1. - ν^2.)/((2. - ν)*(1. + ν)) # Obermayr et al 2011
+
+ else # Micromechanical parameterization: k_n and k_t set explicitly
+ k_n = harmonicMean(simulation.ice_floes[i].contact_stiffness_normal,
+ simulation.ice_floes[j].contact_stiffness_normal)
+
+ k_t =
+ harmonicMean(simulation.ice_floes[i].contact_stiffness_tangential,
+ simulation.ice_floes[j].contact_stiffness_tangential)
+ end
- if delta_n > 0. # Double-check contact
- error("function called to process non-existent contact between ice " *
- "floes $i and $j")
- else
+ γ_n = harmonicMean(simulation.ice_floes[i].contact_viscosity_normal,
+ simulation.ice_floes[j].contact_viscosity_normal)
- # Local axes
- n = p/dist
- t = [-n[2], n[1]]
-
- # Contact kinematics
- vel_lin = simulation.ice_floes[i].lin_vel -
- simulation.ice_floes[j].lin_vel
- vel_n = dot(vel_lin, n)
- vel_t = dot(vel_lin, t) -
- harmonicMean(r_i, r_j)*(simulation.ice_floes[i].ang_vel +
- simulation.ice_floes[j].ang_vel)
-
- # Correct old tangential displacement for contact rotation and add new
- delta_t0 =simulation.ice_floes[i].contact_parallel_displacement[ic]
- delta_t = dot(t, delta_t0 - (n*dot(n, delta_t0))) +
- vel_t*simulation.time_step
-
- # Effective radius
- R_ij = harmonicMean(simulation.ice_floes[i].contact_radius,
- simulation.ice_floes[j].contact_radius) -
- abs(delta_n)/2.
-
- # Contact mechanical parameters
- if simulation.ice_floes[i].youngs_modulus > 0. &&
- simulation.ice_floes[j].youngs_modulus > 0.
-
- E = harmonicMean(simulation.ice_floes[i].youngs_modulus,
- simulation.ice_floes[j].youngs_modulus)
- ν = harmonicMean(simulation.ice_floes[i].poissons_ratio,
- simulation.ice_floes[j].poissons_ratio)
-
- # Contact area
- A_ij = R_ij*min(simulation.ice_floes[i].thickness,
- simulation.ice_floes[j].thickness)
-
- # Effective normal and tangential stiffness
- k_n = E*A_ij/R_ij
- #k_t = k_n*ν # Kneib et al 2016
- k_t = k_n*2.*(1. - ν^2.)/((2. - ν)*(1. + ν)) # Obermayr et al 2011
-
- else # Micromechanical parameterization: k_n and k_t set explicitly
- k_n = harmonicMean(simulation.ice_floes[i].contact_stiffness_normal,
- simulation.ice_floes[j].contact_stiffness_normal)
-
- k_t =
- harmonicMean(simulation.ice_floes[i].contact_stiffness_tangential,
- simulation.ice_floes[j].contact_stiffness_tangential)
- end
+ γ_t = harmonicMean(simulation.ice_floes[i].contact_viscosity_tangential,
+ simulation.ice_floes[j].contact_viscosity_tangential)
- gamma_n = harmonicMean(
- simulation.ice_floes[i].contact_viscosity_normal,
- simulation.ice_floes[j].contact_viscosity_normal)
+ μ_d_minimum = min(simulation.ice_floes[i].contact_dynamic_friction,
+ simulation.ice_floes[j].contact_dynamic_friction)
- gamma_t = harmonicMean(
- simulation.ice_floes[i].contact_viscosity_tangential,
- simulation.ice_floes[j].contact_viscosity_tangential)
+ # Determine contact forces
+ if k_n ≈ 0. && γ_n ≈ 0.
+ force_n = 0.
- mu_d_minimum = min(simulation.ice_floes[i].contact_dynamic_friction,
- simulation.ice_floes[j].contact_dynamic_friction)
+ elseif k_n > 0. && γ_n ≈ 0.
+ force_n = -k_n*δ_n
- # Determine contact forces
- if k_n ≈ 0. && gamma_n ≈ 0.
+ elseif k_n > 0. && γ_n > 0.
+ force_n = -k_n*δ_n - γ_n*vel_n
+ if force_n < 0.
force_n = 0.
-
- elseif k_n > 0. && gamma_n ≈ 0.
- force_n = -k_n*delta_n
-
- elseif k_n > 0. && gamma_n > 0.
- force_n = -k_n*delta_n - gamma_n*vel_n
- if force_n < 0.
- force_n = 0.
- end
-
- else
- error("unknown contact_normal_rheology (k_n = $k_n," *
- " gamma_n = $gamma_n")
end
- if k_t ≈ 0. && gamma_t ≈ 0.
- # do nothing
+ else
+ error("unknown contact_normal_rheology (k_n = $k_n," *
+ " γ_n = $γ_n")
+ end
- elseif k_t ≈ 0. && gamma_t > 0.
- force_t = abs(gamma_t * vel_t)
- if force_t > mu_d_minimum*abs(force_n)
- force_t = mu_d_minimum*abs(force_n)
- end
- if vel_t > 0.
- force_t = -force_t
- end
+ if k_t ≈ 0. && γ_t ≈ 0.
+ # do nothing
- elseif k_t > 0.
+ elseif k_t ≈ 0. && γ_t > 0.
+ force_t = abs(γ_t * vel_t)
+ if force_t > μ_d_minimum*abs(force_n)
+ force_t = μ_d_minimum*abs(force_n)
+ end
+ if vel_t > 0.
+ force_t = -force_t
+ end
- force_t = -k_t*delta_t - gamma_t*vel_t
+ elseif k_t > 0.
- if abs(force_t) > mu_d_minimum*abs(force_n)
- force_t = mu_d_minimum*abs(force_n)*force_t/abs(force_t)
- delta_t = (-force_t - gamma_t*vel_t)/k_t
- end
+ force_t = -k_t*δ_t - γ_t*vel_t
- else
- error("unknown contact_tangential_rheology (k_t = " *
- "$k_t, gamma_t = $gamma_t")
+ if abs(force_t) > μ_d_minimum*abs(force_n)
+ force_t = μ_d_minimum*abs(force_n)*force_t/abs(force_t)
+ δ_t = (-force_t - γ_t*vel_t)/k_t
end
+
+ else
+ error("unknown contact_tangential_rheology (k_t = $k_t, γ_t = $γ_t")
end
- simulation.ice_floes[i].contact_parallel_displacement[ic] = delta_t*t
+
+ simulation.ice_floes[i].contact_parallel_displacement[ic] = δ_t*t
simulation.ice_floes[i].force += force_n*n + force_t*t;
simulation.ice_floes[j].force -= force_n*n + force_t*t;