Despite significant advancements in microfluidics, the development of an efficient technique for the handling of micron-sized objects in a contactless, and biocompatible manner continues to remain a challenge. Acoustofluidics – coupling between ultrasonic sound waves and fluid flows, is an emerging and powerful technique which have proven to possess the above characteristics. However, understanding of the physics of the acoustofluidics phenomena, particularly the acoustic radiation forces is limited, leaving scope for significant research. We elucidated the fundamental understanding of interparticle forces between a pair of particles in a fluid exposed to bulk standing acoustics wave (BSAW) using a numerical model. Perturbation technique and tensor integral method are employed to predict the interparticle radiation force by subtracting the time-averaged primary radiation force due to the scattering effect from the time-averaged total radiation force due to combined scattering and re-scattering effects. Our results reveal that the interparticle force changes from attractive to repulsive at a critical interdistance, attributed to the competition between time-averaged second-order pressure and velocity terms. We found that for a pair of particles parallel to the nodal plane, the interparticle force is independent of their distance from the nodal plane. Considering the total radiation force as the sum of the interparticle force, axial primary force, and drag force, we demonstrated a methodology for experimental quantification of the interparticle force. The interparticle force predicted from the model shows a good agreement with experimental data. Further, we investigated the dynamics of a particle pair placed at a pressure nodal plane exposed to BSAW using experiments and numerical simulations. The insight into their dynamical behavior along the pressure nodal plane due to the competition between the axial primary radiation and interparticle forces is elucidated. An expression for axial primary radiation force acting on a particle is derived, and the particle dynamics are simulated using a fluid-structure interaction model based on the arbitrary Lagrangian-Eulerian (ALE) method. Acceleration, deceleration, and constant velocity motion of the pair of approaching particles are observed, which are explained considering the interplay of the acoustic and non-acoustic forces. The dynamics of the pair of particles predicted using the model are in good agreement with the experimental observation. Our study sheds light on the dynamics of a particle pair exposed to BSAW that will help in better estimation of forces on particles in an acoustic field.