diff --git a/src/setup.jl b/src/setup.jl
index 0a03656..ba3761c 100644
--- a/src/setup.jl
+++ b/src/setup.jl
@@ -4,6 +4,10 @@ const DEFAULT_SKIN_TO_INTERACTION_R_RATIO = 1.5
 const DEFAULT_EXPORTS_DIR = "exports"
 const DEFAULT_PARENT_DIR = ""
 const DEFAULT_COMMENT = ""
+const DEFAULT_PARTICLE_RADIUS = 0.5
+const DEFAULT_Dₜ = 1.0
+const DEFAULT_μ = 1.0
+const DEFAULT_ϵ = 100.0
 
 function initial_particle_grid_pos(
     i::Int64, j::Int64, grid_box_width::Float64, half_box_len::Float64
@@ -55,12 +59,12 @@ function gen_sim_consts(
     @assert δt in 1e-7:1e-7:1e-4
     @assert packing_ratio > 0
 
-    μ = 1.0
-    Dₜ = 1.0
-    particle_radius = 0.5
+    μ = DEFAULT_μ
+    Dₜ = DEFAULT_Dₜ
+    particle_radius = DEFAULT_PARTICLE_RADIUS
     Dᵣ = 3 * Dₜ / ((2 * particle_radius)^2)
     σ = 2 * particle_radius
-    ϵ = 100.0
+    ϵ = DEFAULT_ϵ
     interaction_r = 2^(1 / 6) * σ
 
     buffer = 1.8