A computer-implemented method of modeling an object, the method comprising: defining a state transition probability and a state of each of a plurality of particles forming the object; changing a state of a particle defined to be in a first state among the plurality of particles to a second state; applying a movement model to a particle defined to be in the second state among the plurality of particles; and changing a state of the particle defined to be in the second state to the first state based on the state transition probability, displaying the object based on the plurality of particles, wherein the object is a fluid represented in a virtual space, and the plurality of particles are used to represent the fluid, wherein the first state is a state in which a particle is temporarily stored in a memory after representation of the particle in a scene is terminated and is not displayed, wherein the second state is a state in which particles represent a representative flow of a fluid in a virtual space, the method further comprising: monitoring statistical information associated with the particles in the first state, wherein the statistical information comprises at least one of a memory size occupied by the particles in the first state, a number of particles in the first state, and a ratio of the particles in the first state to particles in another state; comparing the statistical information to a preset threshold; adjusting the state transition probability based on a result of the comparing, such as to make it possible to efficiently reuse particles to model the object by maintaining a sufficient number of particles in the first state. defining a state transition probability and a state of each of a plurality of particles forming the object; changing a state of a particle defined to be in a first state among the plurality of particles to a second state; applying a movement model to a particle defined to be in the second state among the plurality of particles; and changing a state of the particle defined to be in the second state to the first state based on the state transition probability, displaying the object based on the plurality of particles, wherein the object is a fluid represented in a virtual space, and the plurality of particles are used to represent the fluid, wherein the first state is a state in which a particle is temporarily stored in a memory after representation of the particle in a scene is terminated and is not displayed, wherein the second state is a state in which particles represent a representative flow of a fluid in a virtual space, the method further comprising: monitoring statistical information associated with the particles in the first state, wherein the statistical information comprises at least one of a memory size occupied by the particles in the first state, a number of particles in the first state, and a ratio of the particles in the first state to particles in another state; comparing the statistical information to a preset threshold; adjusting the state transition probability based on a result of the comparing, such as to make it possible to efficiently reuse particles to model the object by maintaining a sufficient number of particles in the first state. monitoring statistical information associated with the particles in the first state, wherein the statistical information comprises at least one of a memory size occupied by the particles in the first state, a number of particles in the first state, and a ratio of the particles in the first state to particles in another state; comparing the statistical information to a preset threshold; adjusting the state transition probability based on a result of the comparing, such as to make it possible to efficiently reuse particles to model the object by maintaining a sufficient number of particles in the first state.