page_title: Squirmer
section_title: Velocity field in particle frame
hierarchical_section_title: Squirmer / Velocity field in particle frame
caption_attribution_description: English: Velocity field
context_page_description: The squirmer is a model for a spherical microswimmer swimming in Stokes flow. The squirmer model was introduced by James Lighthill in 1952 and refined and used to model Paramecium by John Blake in 1971.
  Blake used the squirmer model to describe the flow generated by a carpet of beating short filaments called cilia on the surface of Paramecium. Today, the squirmer is a standard model for the study of self-propelled particles, such as Janus particles, in Stokes flow.
context_section_description: Here we give the flow field of a squirmer in the case of a non-deformable axisymmetric spherical squirmer (radius ). These expressions are given in a spherical coordinate system.
  Here  are constant coefficients,  are Legendre polynomials, and . 
  
  One finds .
  
  The expressions above are in the frame of the moving particle. At the interface one finds  and .
caption: Pusher, 
    
      
        
          β
          =
          −
          5
        
      
      {\displaystyle \beta =-5}
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