diff --git a/advanced-reactor.html b/advanced-reactor.html
index 9ea7e23..40ea4f6 100644
--- a/advanced-reactor.html
+++ b/advanced-reactor.html
@@ -8,7 +8,7 @@
             volume: { value: 0., required: true },
             length: { value: 0.},
             resolution_L: { value: 0.},
-            boundary_condition: {value: "Generalised"},
+            alpha: {value: 0},
             n_inlets: { value: 1, required: true},
             kla: { value: null },
             S_O_init: { value: 0., required: true },
@@ -76,17 +76,9 @@
                     $(".PFR").show();
                 }
             });
-            $("#node-input-boundary_condition").typedInput({
-                types: [
-                    {
-                        value: "Generalised",
-                        options: [
-                            { value: "Generalised", label: "Generalised"},
-                            { value: "Dirichlet", label: "Dirichlet"},
-                            { value: "Danckwerts", label: "Danckwerts"}
-                        ]
-                    }
-                ]
+            $("#node-input-alpha").typedInput({
+                type:"num",
+                types:["num"]
             })
             // Set initial visibility on dialog open
             const initialType = $("#node-input-reactor_type").typedInput("value");
@@ -131,9 +123,12 @@
         <label for="node-input-resolution_L"><i class="fa fa-tag"></i> Resolution</label>
         <input type="text" id="node-input-resolution_L" placeholder="#">
     </div>
-        <div class="form-row PFR">
-        <label for="node-input-boundary_condition"><i class="fa fa-tag"></i>Inlet boundary condition</label>
-        <input type="text" id="node-input-boundary_condition">
+    <div class="PFR">
+        <p> Inlet boundary condition parameter &alpha; (&alpha; = 0: Danckwerts BC / &alpha; = 1: Dirichlet BC) </p>
+        <div class="form-row">
+            <label for="node-input-alpha"><i class="fa fa-tag"></i>Adjustable parameter BC</label>
+            <input type="text" id="node-input-alpha">
+        </div>
     </div>
     <div class="form-row">
         <label for="node-input-n_inlets"><i class="fa fa-tag"></i> Number of inlets</label>
diff --git a/src/nodeClass.js b/src/nodeClass.js
index e3c3fd6..7ec81d3 100644
--- a/src/nodeClass.js
+++ b/src/nodeClass.js
@@ -70,7 +70,7 @@ class nodeClass {
             volume: parseFloat(uiConfig.volume),
             length: parseFloat(uiConfig.length),
             resolution_L: parseInt(uiConfig.resolution_L),
-            boundary_condition: uiConfig.boundary_condition,
+            alpha: parseFloat(uiConfig.alpha),
             n_inlets: parseInt(uiConfig.n_inlets),
             kla: parseFloat(uiConfig.kla),
             initialState: [
diff --git a/src/specificClass.js b/src/specificClass.js
index 1124b0d..18af512 100644
--- a/src/specificClass.js
+++ b/src/specificClass.js
@@ -149,7 +149,7 @@ class Reactor_PFR extends Reactor {
         this.d_x = this.length / this.n_x;
         this.A = this.volume / this.length; // crosssectional area [m2]
 
-        this.BC = config.boundary_condition;
+        this.alpha = config.alpha;
 
         this.state = Array.from(Array(this.n_x), () => config.initialState.slice())
 
@@ -208,23 +208,7 @@ class Reactor_PFR extends Reactor {
             const BC_gradient = Array(this.n_x).fill(0);
             BC_gradient[0] = -1;
             BC_gradient[1] = 1;
-            let BC_term = 0;
-            switch(this.BC) {
-                case "Dirichlet":
-                    BC_term = 0;
-                    break;
-                case "Danckwerts":
-                    BC_term = this.D*this.A / math.sum(this.Fs);
-                    break;
-                case "Generalised":
-                    let Pe = this.length * math.sum(this.Fs) / (this.D * this.A);
-                    let residence_time = this.volume/math.sum(this.Fs);
-                    BC_term = (1 - (1 + 4*residence_time/Pe)^0.5) / Pe
-                    break;
-                default:
-                    console.warn("Unknown boundary condition: " + this.BC);
-            }
-            const BC_dispersion = math.multiply(BC_term/this.d_x, [BC_gradient], state)[0];
+            const BC_dispersion = math.multiply((1 - this.alpha) * this.D*this.A / (math.sum(this.Fs) * this.d_x), [BC_gradient], state)[0];
             state[0] = math.add(BC_C_in, BC_dispersion).map(val => val < 0 ? 0 : val);
         } else { // Neumann BC (no flux)
             state[0] = state[1];