A panel assembly (10, 61) comprising: a panel (12, 62), said panel having a panel inner surface (12a, 62b) and a panel outer surface (12b, 62a), said panel further comprising at least one through opening (14, 63); a shape memory alloy component (16, 64), said shape memory alloy component (16, 64) arranged in a moveably abutting orientation and in contact with the panel inner surface (12a, 62b), said shape memory alloy component (16, 64) having a low friction coefficient or being incorporated into a material having a low friction coefficient, said shape memory alloy component (16, 64) having a first dimension in a non-activated state and said shape memory alloy component (16, 64) having at least a second dimension or a plurality of dimensions (d2, d3) in an activated state, said second dimension or plurality of dimensions (d2, d3) different from the first dimension; wherein the shape memory alloy component (16, 64) in the non-activated state and in the activated state is maintained in an orientation in contact with the panel inner surface (12a, 62b);wherein said panel assembly (10, 61) comprises an initial porosity in a non-activated state, and said panel assembly (16, 64) comprises at least one variable porosity in an activated state, said variable porosity different from the initial porosity; wherein the shape memory alloy component (16, 64) performs the function of changing the porosity of the panel assembly (10, 61) by changing dimension from the first dimension to the second dimension or the plurality of dimensions (d2, d3); wherein, in the non-activated state, the shape memory alloy component (16, 64) is aligned with the panel (12, 62) or otherwise positioned and oriented relative to the panel (12, 62) such that the shape memory alloy component (16, 64) blocks the at least one through opening (14, 63) in the panel (16, 64), with the at least one through opening (14, 63) in the panel (12, 62) being closed; wherein, in the activated state, the shape memory alloy component (16, 64) is moved such that the at least one through opening (14, 63) in the panel (12, 62) is not blocked, with the at least one through opening (14, 63) in the panel (12, 62) being open or partially open; and wherein, in the activated state, incident airflow can pass through the at least one through opening (14, 63) in the panel (12, 62). a panel (12, 62), said panel having a panel inner surface (12a, 62b) and a panel outer surface (12b, 62a), said panel further comprising at least one through opening (14, 63); a shape memory alloy component (16, 64), said shape memory alloy component (16, 64) arranged in a moveably abutting orientation and in contact with the panel inner surface (12a, 62b), said shape memory alloy component (16, 64) having a low friction coefficient or being incorporated into a material having a low friction coefficient, said shape memory alloy component (16, 64) having a first dimension in a non-activated state and said shape memory alloy component (16, 64) having at least a second dimension or a plurality of dimensions (d2, d3) in an activated state, said second dimension or plurality of dimensions (d2, d3) different from the first dimension; wherein the shape memory alloy component (16, 64) in the non-activated state and in the activated state is maintained in an orientation in contact with the panel inner surface (12a, 62b);wherein said panel assembly (10, 61) comprises an initial porosity in a non-activated state, and said panel assembly (16, 64) comprises at least one variable porosity in an activated state, said variable porosity different from the initial porosity; wherein the shape memory alloy component (16, 64) performs the function of changing the porosity of the panel assembly (10, 61) by changing dimension from the first dimension to the second dimension or the plurality of dimensions (d2, d3); wherein, in the non-activated state, the shape memory alloy component (16, 64) is aligned with the panel (12, 62) or otherwise positioned and oriented relative to the panel (12, 62) such that the shape memory alloy component (16, 64) blocks the at least one through opening (14, 63) in the panel (16, 64), with the at least one through opening (14, 63) in the panel (12, 62) being closed; wherein, in the activated state, the shape memory alloy component (16, 64) is moved such that the at least one through opening (14, 63) in the panel (12, 62) is not blocked, with the at least one through opening (14, 63) in the panel (12, 62) being open or partially open; and wherein, in the activated state, incident airflow can pass through the at least one through opening (14, 63) in the panel (12, 62).