BIO_flush with BIO_pairs?

[Nate Leon]

Is there any use for BIO_flush when using BIO_pairs?
I am using buffers in a BIO_pair to do en/decryption between the network and
my app.
e.g.:
                                            BIO_pair
                                        ------------------
The <---> WSARecv <---> BIO_write <---> network | internal <---> SSL* <--->
SSL_read

Wire      /Send          /read            BIO      BIO                       /
write


Is BIO_flush ever needed to move data between the network and internal BIO?
Such as:
   BIO_write(networkBio, encryptedData, dwDataSize);
   BIO_flush(networkBio);

Thanks,
Nate