A filter is provided which includes channels for circulation of coolant fluid through the filter, at least one channel extending along a channel centerline and includes an upstream section, a downstream section and an intermediate section extending between the upstream section and the downstream section and being enlarged relative to the upstream section and the downstream section. The filter also includes at least one separating member defining inside the intermediate section of the at least one channel an annular passage whose axis is substantially coaxial to the channel centerline in the intermediate section.