Dry, Aligning, Dilute, Active Matter

Abstract

Abstract Dry, aligning, dilute, active matter (DADAM) refers to a corner of the multidimensional, fast-growing field of active matter. This corner has both historical and theoretical importance for the entire field. This chapter first describes this particular status of DADAM. We then provide an overview of our current knowledge of DADAM. For convenience, we first describe the phenomenology of simple active particle models representing the basic DADAM classes, limiting ourselves to two spatial dimensions, where most work has been performed. Then we discuss the continuous hydrodynamic theories derived from these models using the Boltzmann-Ginzburg-Landau approach. We show in particular that they are largely faithful to the microscopic level, albeit qualitatively. Finally, we come back to the nodal situation of DADAM within active matter studies and provide perspectives on how one can expand DADAM knowledge into various directions, approaching more realistic and more complex situations in a controlled way.