@mirsy Yes, sometimes referred to as a flutter by some people.

“The Aerobika OPEP (Oscillating Positive Expiratory Pressure) device is a hand-held airway clearance device that helps clear mucus and improve breathing.

It works by creating positive pressure and vibrations in the airways, helping to loosen and move mucus.“

Postural drainage works well for some people as well.

Depending on where the mucus is located, even lying down on your back for a minute or two, as you do some deep breathing / exhale using your diaphragm, and then sit up and complete huff, can help. (Placing your arms up behind your head if possible, might be beneficial.) You really have to experiment as others have said and check out the YouTube videos!