If you're using recent leaked Google's Upcoming Nexus Launcher in your device, have surprised from google Nexus Launcher currently in developing mode and that's why no such any fluid animation is available in launcher but, fikar not? today released Google app Beta version (v6.3.30) have added google search app fluid animation.
This shows that Google is moving forward with finishing their new launcher in time for the upcoming Nexus devices. Please note that if you want to see this for yourself, you must be on the latest beta version of the Google app. You can get the latest Search beta APK (v6.3.30) at APK Mirror right here, or via the Play Store if your device shows an update to the app.