<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">Dear Soft Matter Colleagues and Friends,</div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">On Friday 23 October 2020 we will host a seminar during which</div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class=""><b class="">Max Cooper </b>(IFT UW)</div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">will give a talk</div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class=""><b class="">Modeling cave cross-section evolution and the effect of mechanical versus chemical erosion</b></div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class=""><b class="">Abstract</b></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class=""><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">Deposits within caves are often used to interpret past landscape evolution and climate conditions. However, cave passage shapes also preserve information about past conditions. Despite the usefulness of passage shape, numerical models of cave formation neglect cross-section evolution. To address this gap a model for evolving cave passage cross‐sections is developed using a shear stress estimation algorithm and a shear stress erosion rule. The model qualitatively duplicates observed cave passage shapes so long as erosion rates vary with shear stress, as in the case of transport limited dissolution or mechanical erosion. Existing scaling relationships from bedrock channel literature of width to discharge are duplicated, and further explored for varying erosion mechanism. Additionally, this scaling relationship is explored for natural distribution of discharge instead of treatment as a single mean value.</div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">When sediment transport and alluviation is added to the model we successfully simulate paragenetic channels, a type of passage that forms when sediment armors the floor of the cave, forcing upwards erosion under pressurized conditions. An approximate scaling relationship indicates that equilibrium paragenetic channel width scales strongly with discharge, and weakly with the inverse of sediment supply. Simulations confirm the relationship and show that erosion mechanism, sediment size, and roughness are secondary controls.</div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">The model is also adapted to simulate cross-sections of cave meander bends. Simulations of meander cross-sections reveal that the relationship between the contrast in shear stress on either wall and the incision angle of the meander record erosion mechanisms, allowing mechanisms to be determined in the field. Field measurements of such data indicate mechanical erosion plays a larger in the formation of caves than assumed in the karst literature. Totality of modeled cave cross-sections and measured data strongly indicate previous hypotheses of cave formation in turbulent flow need adjustment, and further data must be collected to determine erosion mechanisms in caves.</div></div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">The seminar will be conducted on Zoom</div><div style="margin: 0px; font-stretch: normal; line-height: normal; color: rgb(220, 161, 13);" class=""><span style="text-decoration: underline" class=""><a href="https://zoom.us/j/92987083349?pwd=YTZLSFVWUnJzdE4xS1drR3dqMVFDdz09" class="">https://zoom.us/j/92987083349?pwd=YTZLSFVWUnJzdE4xS1drR3dqMVFDdz09</a></span></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">Meeting ID: 929 8708 3349</div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">Passcode: a8QhyS</div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">and will begin at <b class="">9:30AM</b>. </div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; text-align: justify; font-stretch: normal; line-height: normal;" class="">Everyone is very welcome to attend and ask questions over Zoom. A limited number of participants may be present in the seminar room upon prior agreement.</div><div style="margin: 0px; text-align: justify; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; text-align: justify; font-stretch: normal; line-height: normal;" class="">Maria Ekiel-Jeżewska</div><div style="margin: 0px; text-align: justify; font-stretch: normal; line-height: normal;" class="">Maciej Lisicki</div><div style="margin: 0px; text-align: justify; font-stretch: normal; line-height: normal;" class="">Marek Napiórkowski</div><div style="margin: 0px; text-align: justify; font-stretch: normal; line-height: normal;" class="">Piotr Szymczak</div></body></html>