• Basic forms
• 流す — to let flow; to shed; to play (music) / base form
• 流します — (I) let flow; shed / masu form
• 流した — shed; let flow / ta form
• 流して — let flow and … / te form
• 流さない — do not let flow / negative
• 流せば — if you let it flow / conditional
• 流せ — let it flow! / imperative
• Other common forms
• 涙を流す — to shed tears
• 音楽を流す — to play music
• 流せる — can let flow / potential
• More
• 流さないで — don't let it flow / negative request

流す（ながす） is a godan transitive verb. Used when someone *causes* something to flow (water, tears, music, etc.).

• Basic forms
• 流れる — to flow; to run; to be broadcast / base form
• 流れます — (it) flows / masu form
• 流れた — flowed / ta form
• 流れて — flowing / te form
• 流れない — does not flow / negative
• 流れれば — if it flows / conditional
• Common expressions
• 川が流れる — the river flows
• 音楽が流れる — music is playing
• 涙が流れる — tears flow
• More
• 流れている — is flowing / progressive

流れる（ながれる） is an ichidan intransitive verb. Describes something flowing naturally (water, time, music).