With　the　increased　availability　of　computational　resources,　the　past　decade　has　seen　a　rise　in　the　use　of　computational　fluid　dynamics　(CFD)　for　medical　applications.　There　has　been　an　increase　in　the　application　of　CFD　to　attempt　to　predict　the　rupture　of　intracranial　aneurysms,　however,　while　many　hemodynamic　parameters　can　be　obtained　from　these　computations,　to　date,　no　consistent　methodology　for　the　prediction　of　the　rupture　has　been　identified.　One　particular　challenge　to　CFD　is　that　many　factors　contribute　to　its　accuracy;　the　mesh　resolution　and　spatial/temporal　discretization　can　alone　contribute　to　a　variation　in　accuracy.　This　failure　to　identify　the　importance　of　these　factors　and　identify　a　methodology　for　the　prediction　of　ruptures　has　limited　the　acceptance　of　CFD　among　physicians　for　rupture　prediction.　The　International　CFD　Rupture　Challenge　2013　seeks　to　comment　on　the　sensitivity　of　these　various　CFD　assumptions　to　predict　the　rupture　by　undertaking　a　comparison　of　the　rupture　and　blood-flow　predictions　from　a　wide　range　of　independent　participants　utilizing　a　range　of　CFD　approaches.　Twenty-six　groups　from　15　countries　took　part　in　the　challenge.　Participants　were　provided　with　surface　models　of　two　intracranial　aneurysms　and　asked　to　carry　out　the　corresponding　hemodynamics　simulations,　free　to　choose　their　own　mesh,　solver,　and　temporal　discretization.　They　were　requested　to　submit　velocity　and　pressure　predictions　along　the　center-line　and　on　specified　planes.　The　first　phase　of　the　challenge,　described　in　a　separate　paper,　was　aimed　at　predicting　which　of　the　two　aneurysms　had　previously　ruptured　and　where　the　rupture　site　was　located.　The　second　phase,　described　in　this　paper,　aims　to　assess　the　variability　of　the　solutions　and　the　sensitivity　to　the　modeling　assumptions.　Participants　were　free　to　choose　boundary　conditions　in　the　first　phase,　whereas　they　were　prescribed　in　the　second　phase　but　all　other　CFD　modeling　parameters　were　not　prescribed.　In　order　to　compare　the　computational　results　of　one　representative　group　with　experimental　results,　steady-flow　measurements　using　particle　image　velocimetry　(PIV)　were　carried　out　in　a　silicone　model　of　one　of　the　provided　aneurysms.　Approximately　80%　of　the　participating　groups　generated　similar　results.　Both　velocity　and　pressure　computations　were　in　good　agreement　with　each　other　for　cycle-averaged　and　peak-systolic　predictions.　Most　apparent　＂outliers＂　(results　that　stand　out　of　the　collective)　were　observed　to　have　underestimated　velocity　levels　compared　to　the　majority　of　solutions,　but　nevertheless　identified　comparable　flow　structures.　In　only　two　cases,　the　results　deviate　by　over　35%　from　the　mean　solution　of　all　the　participants.　Results　of　steady　CFD　simulations　of　the　representative　group　and　PIV　experiments　were　in　good　agreement.　The　study　demonstrated　that　while　a　range　of　numerical　schemes,　mesh　resolution,　and　solvers　was　used,　similar　flow　predictions　were　observed　in　the　majority　of　cases.　To　further　validate　the　computational　results,　it　is　suggested　that　time-dependent　measurements　should　be　conducted　in　the　future.　However,　it　is　recognized　that　this　study　does　not　include　the　biological　aspects　of　the　aneurysm,　which　needs　to　be　considered　to　be　able　to　more　precisely　identify　the　specific　rupture　risk　of　an　intracranial　aneurysm.