[Transport] Add IonGasTransport::electricalConductivity

include/cantera/transport/IonGasTransport.h

@@ -73,6 +73,13 @@ public:
     //! The binary transport between two charged species is neglected.
     virtual void getMixDiffCoeffs(double* const d);
 
+    /*! The electrical conductivity (Siemens/m).
+     * \f[
+     *     \sigma = \sum_k{\left|C_k\right| \mu_k \frac{X_k P}{k_b T}}
+     * \f]
+     */
+    virtual double electricalConductivity();
+
 protected:
     //! setup parameters for n64 model
     void setupN64();

src/transport/IonGasTransport.cpp

@@ -127,6 +127,23 @@ double IonGasTransport::thermalConductivity()
     return m_lambda;
 }
 
+double IonGasTransport::electricalConductivity()
+{
+    vector_fp mobi(m_nsp);
+    getMobilities(&mobi[0]);
+    double p = m_thermo->pressure();
+    double sum = 0.0;
+    for (size_t k : m_kIon) {
+        double ND_k = m_molefracs[k] * p / m_kbt;
+        sum += ND_k * abs(m_speciesCharge[k]) * ElectronCharge * mobi[k];
+    }
+    if (m_kElectron != npos) {
+        sum += m_molefracs[m_kElectron] * p / m_kbt *
+               ElectronCharge * mobi[m_kElectron];
+    }
+    return sum;
+}
+
 void IonGasTransport::fitDiffCoeffs(MMCollisionInt& integrals)
 {
     GasTransport::fitDiffCoeffs(integrals);