uent <span class="op">=</span> <span class="fl">1</span>,</span>
<span>  time_influent <span class="op">=</span> <span class="fl">0</span>,</span>
<span>  concentration_initial <span class="op">=</span> <span class="fl">0</span>,</span>
<span>  fracture_aperture <span class="op">=</span> <span class="fl">2e-04</span>,</span>
<span>  fracture_spacing <span class="op">=</span> <span class="fl">1</span>,</span>
<span>  velocity <span class="op">=</span> <span class="fl">0.1</span><span class="op">/</span><span