A fluid actuator for influencing a flow along a flow surface by ejection of a fluid flowing through the fluid actuator, comprising an outlet device equipped with at least two outlet openings (24a, 24b) and at least two outlet lines (22a, 22b) merging into the outlet openings (24a, 24b), and into which there are further integrated: an interaction chamber which is in fluid-communicating connection via a respective flow line (32a, 32b) via a respective outlet line (22a, 22b) with one outlet opening (24a, 24b) each and which comprises a flow dividing device arranged at the inlet of the outlet lines (22a, 22b); a feed line routed to the interaction chamber for supplying fluid at a feed pressure into the interaction chamber; at least two control lines (62a, 62b) for supplying fluid at respective different control pressures into the interaction chamber via at least one respective control opening (64a, 64b); wherein the interaction chamber is realized such that due to supplying fluid through one of the control lines (62a, 62b) in a higher degree than through the other control lines (62a, 62b), the fluid flowing through the feed line in the interaction chamber may correspondingly be deflected in an alternating majoritary manner into one respective outlet line (22a, 22b) associated to this control line (62a, 62b), wherein the fluid actuator is equipped with a control pressure varying device comprising a control feed line and a control flow dividing device which connects the feed line to the control lines (62a, 62b) in a fluid-communicating manner, and a flow body arranged in the control feed line, characterized in that the flow body is realized such that upon application of a flow by means of the control feed line by flowing around the flow body, vortices alternatingly detach from the latter when viewed transversely to the direction of flow, whereby the flow from the control feed line alternatingly arrives majoritarily in a respective one of the control lines (62a, 62b) so as to alternatingly create different control pressures at the control openings (64a, 64b). an interaction chamber which is in fluid-communicating connection via a respective flow line (32a, 32b) via a respective outlet line (22a, 22b) with one outlet opening (24a, 24b) each and which comprises a flow dividing device arranged at the inlet of the outlet lines (22a, 22b); a feed line routed to the interaction chamber for supplying fluid at a feed pressure into the interaction chamber; at least two control lines (62a, 62b) for supplying fluid at respective different control pressures into the interaction chamber via at least one respective control opening (64a, 64b); wherein the interaction chamber is realized such that due to supplying fluid through one of the control lines (62a, 62b) in a higher degree than through the other control lines (62a, 62b), the fluid flowing through the feed line in the interaction chamber may correspondingly be deflected in an alternating majoritary manner into one respective outlet line (22a, 22b) associated to this control line (62a, 62b), wherein the fluid actuator is equipped with a control pressure varying device comprising a control feed line and a control flow dividing device which connects the feed line to the control lines (62a, 62b) in a fluid-communicating manner, and a flow body arranged in the control feed line, characterized in that the flow body is realized such that upon application of a flow by means of the control feed line by flowing around the flow body, vortices alternatingly detach from the latter when viewed transversely to the direction of flow, whereby the flow from the control feed line alternatingly arrives majoritarily in a respective one of the control lines (62a, 62b) so as to alternatingly create different control pressures at the control openings (64a, 64b).