Intracranial　aneurysm　(IA)　is　a　prevalent　cerebrovascular　disease　associated　with　high　mortality　and　disability　rates　upon　rupture.　The　hemodynamics　of　IA,　which　are　significantly　influenced　by　geometric　parameters,　directly　impact　its　rupture.　This　study　focuses　on　investigating　the　transient　flow　characteristics　in　saccular　IA　models　fabricated　using　a　water　droplet-based　method,　specifically　examining　the　influence　of　neck　widths.　Particle　image　velocimetry　technique　and　numerical　simulation　were　employed　to　investigate　the　dynamic　evolution　of　flow　structures　within　three　IA　models.　The　results　reveal　that　neck　width　(W)　has　a　substantial　effect　on　flow　characteristics　in　the　neck　region,　subsequently　impacting　the　deep　flow　inside　the　sac.　Three　distinct　patterns　were　observed　during　flow　evolution　inside　the　sac:　for　W　=　2　mm,　two　vortices　occur　and　then　disappear　with　relatively　low　average　flow　velocity;　for　W　=　4　mm,　enhanced　effects　of　a　high-speed　jet　result　in　periodic　pulsatile　flow　velocity　distribution　while　maintaining　stable　vortex　core　position;　for　W　=　6　mm,　significant　changes　in　flow　velocity　occur　due　to　size　expansion　and　intensity　increase　of　vortices.　These　findings　demonstrate　that　neck　widths　play　a　complex　role　in　influencing　transient　flow　characteristics　within　IAs.　Overall,　this　research　contributes　to　further　understanding　transient　flow　behaviors　in　IAs.　©　The　Chinese　Society　of　Theoretical　and　Applied　Mechanics　and　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature　2024.