commit b43f3bbd228f43e90ce1c74ad8ae94f08369fbcb
parent 36783cd1acd10f5a76553357199cb8e65ad53b4a
Author: Anders Damsgaard <andersd@riseup.net>
Date: Thu, 8 Feb 2018 10:14:36 -0500
Clarify expression for ocean and atmosphere drag
Diffstat:
2 files changed, 12 insertions(+), 15 deletions(-)
diff --git a/src/atmosphere.jl b/src/atmosphere.jl
@@ -211,13 +211,11 @@ grain.
"""
function applyAtmosphereDragToGrain!(grain::GrainCylindrical,
u::Float64, v::Float64)
- rho_a = 1.2754 # atmosphere density
- length = grain.areal_radius*2.
- width = grain.areal_radius*2.
+ ρ_a = 1.2754 # atmosphere density
- drag_force = rho_a *
- (.5*grain.ocean_drag_coeff_vert*width*.1*grain.thickness +
- grain.atmosphere_drag_coeff_horiz*length*width) *
+ drag_force = ρ_a * π *
+ (2.0*grain.ocean_drag_coeff_vert*grain.areal_radius*.1*grain.thickness +
+ grain.atmosphere_drag_coeff_horiz*grain.areal_radius^2.0) *
([u, v] - grain.lin_vel)*norm([u, v] - grain.lin_vel)
grain.force += drag_force
@@ -233,10 +231,10 @@ and Boucher, 1999.
"""
function applyAtmosphereVorticityToGrain!(grain::GrainCylindrical,
atmosphere_curl::Float64)
- rho_a = 1.2754 # atmosphere density
+ ρ_a = 1.2754 # atmosphere density
grain.torque +=
- pi * grain.areal_radius^4. * rho_a *
+ π * grain.areal_radius^4. * ρ_a *
(grain.areal_radius / 5. * grain.atmosphere_drag_coeff_horiz +
.1 * grain.thickness * grain.atmosphere_drag_coeff_vert) *
abs(.5 * atmosphere_curl - grain.ang_vel) *
diff --git a/src/ocean.jl b/src/ocean.jl
@@ -328,13 +328,12 @@ floe.
function applyOceanDragToGrain!(grain::GrainCylindrical,
u::Float64, v::Float64)
freeboard = .1*grain.thickness # height above water
- rho_o = 1000. # ocean density
+ ρ_o = 1000. # ocean density
draft = grain.thickness - freeboard # height of submerged thickness
- length = grain.areal_radius*2.
- width = grain.areal_radius*2.
- drag_force = rho_o * (.5*grain.ocean_drag_coeff_vert*width*draft +
- grain.ocean_drag_coeff_horiz*length*width) *
+ drag_force = ρ_o * π *
+ (2.0*grain.ocean_drag_coeff_vert*grain.areal_radius*draft +
+ grain.ocean_drag_coeff_horiz*grain.areal_radius^2.0) *
([u, v] - grain.lin_vel)*norm([u, v] - grain.lin_vel)
grain.force += drag_force
@@ -351,11 +350,11 @@ and Boucher, 1999.
function applyOceanVorticityToGrain!(grain::GrainCylindrical,
ocean_curl::Float64)
freeboard = .1*grain.thickness # height above water
- rho_o = 1000. # ocean density
+ ρ_o = 1000. # ocean density
draft = grain.thickness - freeboard # height of submerged thickness
grain.torque +=
- pi * grain.areal_radius^4. * rho_o *
+ π * grain.areal_radius^4. * ρ_o *
(grain.areal_radius/5. * grain.ocean_drag_coeff_horiz +
draft * grain.ocean_drag_coeff_vert) *
abs(.5 * ocean_curl - grain.ang_vel) * (.5 * ocean_curl - grain.ang_vel)
