Does the following nullify wudoo':

1. Vomitting

2. Knee getting revealed

3. Being unclothed during the ritual bath?

1. There is no sound evidences that show that vomiting nullifies wudoo' so in this case, it does not invalidate it.[1]
2. Wudoo’ will still be valid
3. Wudoo is still valid.

Reference:

[1] Dr S Al-Fawzan, A Summary of Islamic Jurisprudence, 1/53 - 58