diff --git a/src/run.jl b/src/run.jl
index af311e2..4daa814 100644
--- a/src/run.jl
+++ b/src/run.jl
@@ -6,7 +6,7 @@ function run_sim(
     dir::String;
     duration::Float64,
     snapshot_at::Float64=0.1,
-    n_steps_before_verlet_list_update::Int64=1000,
+    n_steps_before_verlet_list_update::Int64=100,
     seed::Int64=42,
     n_bundle_snapshots::Int64=100,
 )
@@ -94,7 +94,7 @@ function run_sim(
         save_data = true
 
         open("$runs_dir/run_vars_$next_bundle.json", "w") do f
-            JSON3.pretty(f, run_vars)
+            JSON3.write(f, run_vars)
         end
     else
         save_data = false
diff --git a/src/setup.jl b/src/setup.jl
index 2834dc8..be5a27c 100644
--- a/src/setup.jl
+++ b/src/setup.jl
@@ -38,7 +38,12 @@ function generate_particles(bundle::Bundle, N::Int64)
 end
 
 function init_sim(;
-    N::Int64, v::Float64, δt::Float64=1e-5, packing_ratio::Float64=0.5, comment::String=""
+    N::Int64,
+    v::Float64,
+    δt::Float64=1e-5,
+    packing_ratio::Float64=0.5,
+    comment::String="",
+    parent_dir::String="",
 )
     @assert N > 0
     @assert v >= 0
@@ -83,11 +88,21 @@ function init_sim(;
     bundle = Bundle(N, 1)
     save_snapshot!(bundle, 1, 0.0, particles)
 
-    dir = "exports/$(now())_N=$(N)_v=$(v)_#$(rand(1000:9999))$comment"
+    particles = nothing
+
+    dir = "exports"
+    if length(parent_dir) > 0
+        dir *= "/$parent_dir"
+    end
+    dir *= "/$(now())_N=$(N)_v=$(v)_#$(rand(1000:9999))"
+    if length(comment) > 0
+        dir *= "_$comment"
+    end
+
     mkpath(dir)
 
     open("$dir/sim_consts.json", "w") do f
-        JSON3.pretty(f, sim_consts)
+        JSON3.write(f, sim_consts)
     end
 
     save_bundle(dir, bundle, 1, 0.0)