Like the horn, the flute blends extremely well with all instrument groups. Particularly good blends are achieved with the woodwinds and the strings.
Flute + woodwinds
Flute + flute
Two flutes in unison sound absolutely homogeneous, as do two flutes doubling an octave apart (whether concert flutes or piccolos).
In order to compensate for the lack of volume in the low register, several flutes are used playing in unison.
Flute + oboe, clarinet
The combination of flutes with oboes and clarinets sounds warm and mellow whether played in unison or in octaves.
Flute + bassoon
The flutes are combined with the bassoon either one or even two octaves apart, which produces an exotic effect.