diff --git a/advanced-reactor.js b/advanced-reactor.js
index 8348137..e2eca51 100644
--- a/advanced-reactor.js
+++ b/advanced-reactor.js
@@ -78,6 +78,9 @@ module.exports = function(RED) {
                 case "OTR":
                     reactor.setOTR = msg;
                     break;
+                case "Dispersion":
+                    reactor.setDispersion = msg;
+                    break;
                 default:
                     console.log("Unknown topic: " + msg.topic);
             }
diff --git a/dependencies/reactor_class.js b/dependencies/reactor_class.js
index 4027690..e030637 100644
--- a/dependencies/reactor_class.js
+++ b/dependencies/reactor_class.js
@@ -94,7 +94,7 @@ class Reactor_PFR {
         this.Fs = Array(n_inlets).fill(0.0); // fluid debits per inlet [m3 d-1]
         this.Cs_in = Array.from(Array(n_inlets), () => new Array(13).fill(0.0)); // composition influents
         this.OTR = 0.0; // oxygen transfer rate [g O2 d-1]
-        this.D = 0.1; // axial dispersion [m2 d-1]
+        this.D = 0.0; // axial dispersion [m2 d-1]
         
         this.kla = kla; // if NaN, use external OTR [d-1]