12 - Advective Diffusive Flux =========================================================================== This example corresponds to the "Example 12-Advective and Diffusive Flux of Heat and Solutes" from the Phreeqc manual. It can be retrieved from the `Phreeqc Website `_. The following example demonstrates the capability of PHREEQC to calculate transient transport of heat and solutes in a column or along a 1D flowline. A column is initially filled with a dilute KCl solution at 25 °C in equilibrium with a cation exchanger. A KNO 3 solution then advects into the column and establishes a new temperature of 0 °C. Subsequently, a sodium chloride solution at 24 °C is allowed to diffuse from both ends of the column, assuming no heat is lost through the column walls. At one end, a constant boundary condition is imposed, and at the other end, the final cell is filled with the sodium chloride solution and a closed boundary condition is prescribed. For the column end with a constant boundary condition, an analytical solution is compared with PHREEQC results, for unretarded Cl - (R = 1.0) and retarded Na + and temperature ( R = 3.0). Finally, the second-order accuracy of the numerical method is verified by increasing the number of cells by a factor of three and demonstrating a decrease in the error of the numerical solution by approximately one order of magnitude relative to the analytical solution. Studies -------------------- This project contains **1** Studies. * PhreeqcStudy: **"study_12 - Advective Diffusive Flux"** Db used: **"Phreeqc_dat"** database .. raw:: html :file: study_12 - Advective Diffusive Flux.html Plots -------------------- This project contains **1** Plots. * Plot 1: **"Diffusion of Solutes and Heat"** .. figure:: DiffusionofSolutesandHeat.svg :scale: 100 :alt: DiffusionofSolutesandHeat.svg :align: center